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PROGRAM AND ABSTRACTS BOOKLET

XL CALPHAD

Computer Coupling of Phase Diagrams and Thermochemistry

May 22nd to 27th, 2011

Rio de Janeiro – RJ – Brazil

Certificaçãode Pessoas

OPC 0009

Rua Antonio Comparato, 218 – Campo Belo04605-030 – São Paulo – SP – Brasil

Tel.: (55 11) 5534-4333 – Fax: (55 11) 5534-4330http://www.abmbrasil.com.br

The opinions expressed in the publication are exclusively the responsibility of its authors and does not express

the opinion nor receive the endorsement of ABM.

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logos.indd 1 11/05/2011 11:24:06

ABM EXECUTIVE BOARD

PresidentNelson Guedes de Alcântara

Vice-PresidentAlfredo Huallem

Council PresidentKarlheinz Pohlmann

Executive DirectorHoracídio Leal Barbosa Filho

Patrimony DirectorHideyuki Hariki

DirectorsAntenor Fereira Filho

Antonio Siqueira VianaCarlos Alberto Briganti

Carlos Cunha Dias HenriquesCarlos de Moura NetoDelmar Barros Ribeiro

Evando Mirra de Paula e SilvaHermenio Pinto Gonçalves

Márcio Frazão Guimarães LinsMarcos Alexandre Stuart Nogueira

Renato Cesar Brito de MouraRogério Tales Silva Carneiro

Sérgio Leite de AndradeSérgio Neves Monteiro

Simone Kaukal Valadares

Events ManagerRosangela Ziliotte

Event OrganizersErika Akashi

Margareth Nunes

SupportAlessandra Gonsales

Renata Puga

ORGANIZING COMMITTEECoordinators

André Luiz Vasconcellos da Costa e Silva – EEIMVR-UFF / IBQNFernando Cosme Rizzo Assunção – CGEE / PUC-Rio

MembersAntônio Cezar Faria Vilela – UFRGS

Antonio Ramirez – LNLS-CNPqAntônio Sérgio Fonseca – V&M

Carlos Ângelo Nunes – EEL-USPCarlos Antonio da Silva – UFOP-RedematCelso Antonio Barbosa – Villares Metals

Claudio Schon – EPUSPFlávio Beneduce Neto – UNIFEI

Gilberto Carvalho Coelho – EEL-USPHamilton Ferreira Gomes de Abreu – UFC

João Luiz Barros Antunes – UsiminasJoaquim Gonçalves Costa Neto – ArcelorMittal Monlevade

Nestor Heck– UFRGSPedro Gutemberg – Vale

Raimundo Fortes – GerdauRoberto Ribeiro de Avillez – PUC-Rio

Ronaldo Antonio Neves Barbosa – UFMGWagner Bielefeld – UFRGS

National Scientific CommitteeAndré Luiz Vasconcellos da Costa e Silva – EEIMVR-UFF / IBQN

Antônio Cezar Faria Vilela – UFRGSAntonio Ramirez – LNLS-CNPqCarlos Ângelo Nunes – EEL-USP

Carlos Antonio da Silva – UFOP-RedematClaudio Schon – EPUSP

Fernando Cosme Rizzo Assunção – CGEE / PUC-RioFlávio Beneduce Neto – IPT-SP / UNIFEI

Gilberto Carvalho Coelho – EEL-USPHamilton Ferreira Gomes de Abreu – UFC

Nestor Heck– UFRGSRoberto Ribeiro de Avillez – PUC-Rio

Ronaldo Antonio Neves Barbosa – UFMGTsuneharu Ogasawara † in memorian – Coppe-UFRJ

ORGANIZING COMMITTEEInternational Scientific Committee

Alan Dinsdale - National Physical Laboratory - EnglandArmando Fernandez-Guillermet - Instituto Balsero, CNEA - Argentina

Arthur Pelton - École Polytechnique, Montreal - CanadaBo Sundman - KTH - Sweden, INSTN - France

Byeong-Joo Lee - Postech - KoreaCatherine Colinet - University Montpellier South of France - France

Gabriele Cacciamani - University of Genoa - ItalyHyuck Mo Lee - Kaist - Korea

Jan Vrestal - Masaryk University Brno - Czech RepublicJean Claude Tedenac - University Montpellier South of France - France

John Agren - KTH - SwedenJuan M. Sanchez - University of Texas - USAKiyohito Ishida - Tohoku University - JapanLarry Kaufman - Founding editor, Calphad

Mats Hillert - KTH - SwedenPatrice Turchi - Lawrence Livermore National Laboratory - USA

Peter F. Rogl - University of Vienna - AustriaRainer Schmid-Fetzer - Clausthal University of Technology - Germany

Suzana Fries - Ruhr-Universität Bochum - GermanyTetsuo Mohri - University of Hokkaido - Japan

Tomas Gomez-Acebo - University of Navarra - SpainUrsula Kattner - NIST - USA

Yong Du - ChinaZi-Kui Lui - Penn State University - USA

Table of Contents

Program at a Glance ............................................................................................ 7

Venue ..................................................................................................................... 8

General Information ............................................................................................ 8

List of Oral Presentations ................................................................................... 9

Abstracts (Oral Presentation) ........................................................................... 17

List of Poster Presentations ............................................................................ 111

Abstracts (Poster Presentation) ...................................................................... 117

Authors Index................................................................................................... 228

List of Participants .......................................................................................... 234

7

Program at a Glance

XL CALPHAD - Computer Coupling of Phase Diagrams and ThermochemistryMay 22 (Sun) May 23 (Mon) May 24 (Tue) May 25 (Wed) May 26 (Thu) May 27 (Fri)

7:00 AM BreakfastBreakfast Breakfast Breakfast Breakfast

8:20 AM Welcome remarks8:30 AM

Session 5 Session 9 Session 11Session 15

8:50 AM

Session 1

9:20 AM9:40 AM

10:00 AM10:20 AM

Coffee-break10:40 AM

Coffee-break Coffee-break Coffee-break10:45 AM

Session 16

10:50 AMCoffee-break

11:05 AM

Session 6 Session 10 Session 12

11:15 AM

Session 2

11:35 AM11:55 AM12:15 PM12:35 PM Closing session01:00 PM

Lunch Lunch Lunch Lunch01:05 PM Lunch02:30 PM

Session 3 Session 7

Conference excursion

Session 13

03:00 PM03:20 PM03:40 PM04:00 PM

Registration

04:20 PM04:30 PM

Coffee-break04:40 PMCoffee-break

Coffee-break04:55 PM05:00 PM

Session 8 Session 14

05:05 PM

Session 4

05:25 PM05:45 PM06:05 PM06:25 PM06:45 PM07:00 PM

Welcome cocktail

07:05 PMDinner07:10 PM

Dinner Dinner08:00 PM

Conference dinner

08:30 PM

Coffee-break Poster session Poster session09:00 PM10:00 PM

–10:30 PM

8

Venue

Hotel Intercontinental Rio Avenida Aquarela do Brasil, 75 - São Conrado 22610-010 - Rio de Janeiro - RJ Phone: +55 (21) 3323-2200

General Information

SecurityYour safety and well-being are assured during the event by means of a civil liability insurance policy insurance policy through Rana Seguros.Phone: +55 (11) 3214-6232 - www.ranaseguros.com.br

Special Tourist Assistance Police StationAv. Afrânio de Melo Franco (at Rua Humberto de Campos, 315) – Leblon – Rio de Janeiro – RJPhone: +55 (21) 2332-2924

Tours & Events - Official AgencyRua Barata Ribeiro, 543/706 – Copacabana – Rio de Janeiro – RJPhone: +55 (21) 2545-5748

AirportsRio de Janeiro International Airport / Galeão – Antonio Carlos JobimAv. 20 de Janeiro s/n – Ilha do Governador – Rio de Janeiro – RJPhone: +55 (21) 3398-5050Distance to Hotel Intercontinental Rio: 30 km

Santos Dumont AirportPraça Senador Salgado Filho s/n - Centro – Rio de Janeiro – RJPhone: +55 (21) 3814-7070Distance to Hotel Intercontinental Rio: 10 km

EletricityRio de Janeiro and Sao Paulo have 110 or 120 Volt 60 cycles alternate current (AC). Salvador and Manaus have 127 Volts. Recife, Brasilia and a number of other cities have 220-Volt Service. Most Hotels, however, provide both services and/or adapters for guests.

9

CALPHAD XL, 2011 May 22th - 27th, Rio de Janeiro, Brazil

Monday (Morning), May 23Ab Initio

08:20 Welcome remarks

ChairsDr. Patrice Turchi

Prof. Fernando Rizzo

[O1]08:50

J.M. Sanchez The Cluster Expansion Method: First Principles or Phenomenology?

[O2]09:20

Jörg Neugebauer, Blazej Grabowski, Albert Glensk, and Tilmann Hickel Accuracy and limitations of ab initio approaches in predicting free energies for binaries and unstable phases

[O3]09:50

Helena Maria Petrilli, Ney Sodré, Pablo Guillermo Gonzales-Ormeño, Claudio Geraldo SchonAb-initio calculation of the bcc order/disorder relations in the Al - Cr - Fe (Aluminum - Chromium - Iron) system

[O4]10:10

Benjamin Burton, A. van de WalleFirst Principles Phase Diagram Calculations for the systems: SiC-AlN; SiC-GaN; SiC-InN; and ZrO_X (0 < X < 1)

[O5]10:30

Gilles Hug, Philippe Jund, Romain Viennois, Catherine Colinet, Jean-Claude TédenacAb initio modeling in the Mg-Si system

10:50 Coffee-break

ChairsProf. Catherine ColinetProf. Igor A. Abrikosov

[O6]11:15

Tetsuo MohriProgress of theoretical study of alloy phase equilibria based on Cluster Variation Method

[O7]11:45

Jan Vřesťál, Jana PavlůLaves phases in the Hf-V and V-Zr systems: Stability analysis using ab initio data and phase diagrams

[O8]12:05

J. Pavlů, J. Vřešťál, M. ŠobEnergetics and magnetism of Mo-based sigma phases

[O9]12:25

Susana Ramos de Debiaggi, Críspulo Deluque Toro, Gabriela F. Cabeza, Armando Fernández GuillermetThermodynamic properties of M-In-Sn (M = Cu, Ni) intermetallics: Ab initio database and systematics

[O10]12:45

Anjali Talekar, Dhanesh ChandraTernary Phase Diagrams for Plastic Crystal Energy Storage Materials - Computational and Experimental Approach

13:05 Lunch

10


ChairsProf. Jan Vrestal

Prof. Cláudio G. Schon

[O11]14:30

Igor Abrikosov, Björn Alling, Marcus Ekholm, Hans Lind, Ferenc TasnadiConfigurational thermodynamics of multicomponent complex alloy systems from first-principles theory

[O12]15:00

S.R.Nishitani, K. Togase, Y. Ohno, Y. Tokumoto, and I. YonenagaFirst principles calculations of stacking fault energy of P doped Si crystal

[O13]15:20

Sung Hoon Lee, Zi-Kui LiuComputational and experimental investigations of defects and stability of (La1-xCax)FeO3-δ perovskites

[O14]15:40

Torsten Markus, Jens Emmerlich, Denis Music, Li YangPhase stability and thermomechanical properties of LSCF and BSCF perovskites

[O15]16:00

Jianchuan Wang, Yong Du, Honghui Xu, Lixian Sun, Zi-Kui LiuFormation and migration of native defects in complex hydrides

[O16]16:20

Byeong-Joo Lee, Je-Wook Jang, Kyu-Seok Han, Chan-Hee HanA comparative analysis of the effect of particle pinning and solute segregation on the inhibition of grain boundary movement

16:40 Coffee-break

ChairsProf. Tetsuo Mohri

Prof. Byeong-Joo Lee

[O17]17:05

Patrice E. A. Turchi, Alexander I. LandaActinide alloys and their challenges

[O18]17:35

Catherine Colinet, Jean-Claude TedenacStructural stability of the ternary compounds Mo5SiB2 and Nb5SiB2

[O19]18:05

Jean-Marc Joubert, Aurore Mascaro, Jean-Claude Crivello, Caroline Toffolon-MascletAb-initio calculations of Er-H compounds: application to the modelling of the phase diagram

[O20]18:25

J.-C. Crivello, M. Palumbo, T. Hammerschmidt, S.G. Fries, J.-M. JoubertCalculating heats of formation using DFT: guidelines for the study of TCP phases

[O21]18:45

Wei Xiong, Pavel Korzhavyi, Qing Chen, Malin SellebyBridging ab initio and CALPHAD by a robust magnetic model

19:05 Dinner

20:30Poster Session

22:30

Monday (Afternoon), May 23

11


Tuesday (Morning), May 24The CALPHAD Method, and Assessments

ChairsDr. Larry Kaufman

Dr. Suzana Fries

[O22]08:30

John ÅgrenCalphad - what did we hope for, what did we get - where do we go?

[O23]09:00

Reza Naraghi, Malin SellebyReassessment of the thermodynamic description of the Fe-C system

[O24]09:20

D. Chandra, A. Talekar, J. Lamb,W-M Chien, D. Phanon, Nicolas Penin, Radovan Černý, Klaus Yvon, J-C Crivello, M. Latroche, and M. GuptaTernary Phase Diagram of Li-N-H Complex Hydrides for Hydrogen Storage Systems

[O25]09:40

Chonghe LiThermodynamic Assessment of V2O3-TiO2 System

[O26]10:00

F. Stein, M. Palm, S. Voß, C. He, O. Dovbenko and O. PrymakExperimental investigations of phases, phase equilibria, and melting behaviour in the systems Fe-Al-Nb and Co-Al-Nb and their terminal binary systems

[O27]10:20

Hang Wang, Nils Warnken, Roger C. ReedPhase Field Simulation on beta/alpha transformation in TiAlV system coupled with CALPHAD assessment

10:40 Coffee-break

ChairsProf. John Ågren

Prof. Armando Guillermet

[O28]11:05

Larry KaufmanComputation materials design

[O29]11:35

E. Povoden-Karadeniz, E. Eidenberger, P. Lang, H. Leitner, E. KozeschnikThermodynamics of the Fe-Co-Mo system and modeling of early precipitation in Fe-25 at.% Co-9 at.% Mo alloy

[O30]11:55

Mehdi HosseinifarExperimental investigation and thermodynamic optimization of the Al-Mg-Nd system

[O31]12:15

E. Povoden-Karadeniz, P. Warczok, P. Lang, A. Falahati, M.R. Ahmadi, E. KozeschnikThermodynamic modeling of metastable phases in Al-Cu-Fe-Mg-Mn-Si and applications to precipitation kinetics simulations

[O32]12:35

Peng Zhou, Senlin Cui, Dandan Liu, Lijun Zhang, Yong Du, Wanqi JieAssessment of the atomic mobilities for Fcc_a1 and Bcc_A2 Cu-Fe-Zn alloys

13:00 Lunch

12


ChairsDr. Bo Sundman

Dr. Ursula R. Kattner

[O33]14:30

K. Ishida, T. OmoriNew Co-base Superalloys - Phase Equilibria and Applications

[O34]15:00

M. Palumbo, S. G. Fries, T. Hickel, A. Dal Corso, M. H. G. Jacobs, U. R. Kattner, B. SundmanThe challenge of covering thermodynamic properties not only at high temperature but also at low temperature: a progress report

[O35]15:20

Dmitri V. MalakhovNon-statistical thermodynamic optimization: an irrelevant topic or a useful approach?

[O36]15:40

Patrice Berthod, Lionel Aranda, Ophélie Hestin, Elise Souaillat, Moussa Ba, Ahmed DiaExperimental and thermodynamic study of ternary Ni-30Cr-xC and Co-30Cr-yC carbon-rich alloys with x and y vary-ing from 2.5 to 5.0 wt.%

[O37]16:00

Dominika Jendrzejczyk-Handzlik, Wojciech Gierlotka, Krzysztof FitznerThermodynamic properties and phase equilibria in gold-antimony-tin system determined from E.M.F., Calorimetric, and dta/dsc methods

[O38]16:20

Olga Fabrichnaya, Hans J SeifertExperimental study and thermodynamic modelling of phase relations in the ZrO2-Sm2O3-Y2O3 and Sm2O3-Y2O3-Al2O3 systems

16:40 Coffee-break

ChairsProf. Dr. Rainer Schmid-Fetzer

Prof. Roberto R. de Avillez

[O39]17:00

Suzana G. FriesThe role of CALPHAD in the Science of Materials

[O40]17:30

Yun Hwan Jo, Inyu Jung and Hyuck Mo LeeSynthesis of Size and Composition Controlled Sn-xCu Nanoparticles: Effect on the Phase Diagram and Application to Highly Conductive Ink

[O41]17:50

In-Ho Jung, Marie-Aline Van Ende, Hanshin Choi, Taek-Soo KimThermodynamic Database Development of the Nd-Fe-B-Mg System for the Nd-Fe-B Magnet Scrap Recycling Process

[O42]18:10

Shihuai Zhou, R.E. NapolitanoNonequilibrium phase transformation calculation with Energetics

[O43]18:30

Biao Hu, Honghui Xu, Shuhong Liu, Yong Du, Cuiyun He, Chunsheng Sha, Wenqing Zhang, Yingbiao Peng, Dongdong Zhao and Yiwei LiExperimental investigation and thermodynamic calculation of the Mn-Ni-Si System

[O44]18:50

Atta Ullah Khan, Pavel Broz, Haiyang Niu, Xingqiu Chen, Peter Rogl The Phase Diagrams Ta-V-{Si,Ge}

19:10 Dinner

20:30Poster Session

22:30

Tuesday (Afternoon), May 24

13


Wednesday (Morning), May 25Applications - Energy

ChairsDr. Christine Gueneau

Prof. Bo Sundman

[O45]08:30

Rogl Peter Franz, Noel HenriThe Phase Diagram Basis U - M -Si for LEU fuels; M=Al, Sc to Pt

[O46]09:00

Jeong-Yong Park, Hyun-Gil Kim, Byung-Kwon Choi, Sang-Yoon Park, Yang-Il Jung, Dong-Jun ParkExperimental study on the microstructure factors controlling the corrosion behavior of Zr alloys

[O47]09:20

C. Toffolon-Masclet, C. Desgranges, B. Mazères, D. MonceauSimulation of Oxide Dissolution in Zr Alloys : Comparison between Numerical EKINOX Code and DICTRA Calculations

[O48]09:40

O. Beneš, R. J. M. Konings, D. StaicuPhysico-chemical properties investigation of plutonium

[O49]10:00

M. Beilmann, O. Benes, R. KoningsThermodynamic assessment of a Molten Salt Reactor fuel

[O50]10:20

X.J. Liu, C.P. WangThe thermodynamic database of nuclear material system

10:40 Coffee-break

ChairsDr. Ales Kroupa

Prof. Kiyohito Ishida

[O51]11:05

Gueneau Christine, Gotcu Petronela, Benes Ondrej, Sundman Bo, Dupin Nathalie, Konings R.J.M.Thermodynamic modelling of oxide fuels containing minor actinides (U, Pu, Am, Np)O2±x

[O52]11:35

Ligang Zhang, Patrick J. MassetInvestigation in the CaO-SiO2-M2O (M = Na, K) system

[O53]11:55

Marc A. Duchesne, Robin W. Hughes, Dennis Y. Lu, David McCalden, Arturo Macchi, Edward J. AnthonyApplication of FactSage for the Study of Slagging In Entrained-Flow Gasifiers

[O54]12:15

Patrick Masset, Cuiping GuoEvaluation of the thermodynamic properties of the gas phase involved in gasification processes

[O55]12:35

Jean-Christophe Dumas, Jean-Paul Piron, Chantal MartialEvaluation of the Chemical Composition of Irradiated Mixed Carbide Fuel

13:00 Lunch

14:30Conference Excursion: Visit to Fort São João in Rio de Janeiro;

Visit to Sugar Loaf

20:00Conference Dinner: PORCÃO Rio’s

22:30

14


Thursday (Morning), May 26Applications - Steel, Superalloys, Oxides

ChairsProf. Andre Costa e Silva

Prof. Malin Selleby

[O56]08:30

Tooru MatsumiyaApplications of CALPHAD in Steelmaking and Future Scope

[O57]09:00

André SchneiderApplication of the CALPHAD method for ferritic boiler steels

[O58]09:20

Carlos Cicutti, Constantino CapurroDevelopment of a model to predict inclusions composition in steels deoxidized with aluminum, silicon and manganese

[O59]09:40

Bernd BöttgerPhase-Field Modelling of Technical Alloy Systems

[O60]10:00

T. Gómez-Acebo, F. CastroDiffusion in Fe-Ni PM alloys: microstructure and DICTRA simulations

[O61]10:20

Philippe Schaffnit, Juliane Mentz, Joachim KonradSimulation of an Industrial Solidification Process by Coupling CALPHAD and Phase-Field

10:40 Coffee-break

ChairsProf. Dr. Jorg Neugebauer

Prof. Dr. Herbert Ipser

[O62]11:05

Malin SellebyHow applications drive thermodynamics towards fundamental considerations

[O63]11:35

Henrik Strandlund, Susanne NorgrenApplications of CALPHAD in Cemented carbide development

[O64]11:55

B. Jansson, J. M. Ullbrand, F. Tasnádi, L. Hultman, and M. OdénA multi scale modeling approach for transition metal nitride alloy coatings

[O65]12:15

Qing ChenChallenges of Precipitation Kinetic Modelling. I. Study on Growth Rate Models

[O66]12:35

Ikuo Ohnuma, Shota Shimenouchi, Toshihiro Omori, Ryosuke Kainuma, Kiyohito IshidaPhase Equilibria at Low Temperatures (< 600 °C) and Thermodynamic Evaluation in the Fe-base Binary Systems

13:00 Lunch

15


ChairsDr. Alan J. Ardell

Prof. Dr. Adolf Mikula

[O67]14:30

Bo Sundman, Christine Gueneau, Nathalie DupinThermodynamic modelling of defects in U-Pu-O-C

[O68]15:00

Herbert Ipser, Ratikant MishraThe Ternary Ni-Sb-Sn System: Phase Diagram and Thermochemistry

[O69]15:20

Joo Hyun ParkApplications of Computational Thermodynamics on the Fundamental Research on the Complex Metal-Oxide Systems

[O70]15:40

Christian Robelin, Patrice ChartrandOverview of the Molten Chlorides, Fluorides and Chloro-fluorides Databases of the FactSage Thermochemical Software

[O71]16:00

Patrice Chartrand, Christian Robelin, Matthias Heyrman, Nagendra TripathiThe Cryolite Database for the Hall-Heroult Alumina Reduction Process

[O72]16:20

Viktoria Prostakova, Jeff Chen, Eugene Jak, Sergei A. DecterovDevelopment of a thermodynamic database for Ni-containing oxide systems for simulation of Ni extraction from laterite ores

16:40 Coffee-break

ChairsDr. Ursula R. Kattner

Dr. Caroline Toffolon-Masclet

[O73]17:00

Armando Fernández GuillermetGibbs energy assessment for stable and metastable compounds: experiments, phenomenology and theory

[O74]17:30

Nils Warnken, Roger C ReedA design driven Superalloy development approach

[O75]17:50

Alan J. ArdellInterfacial Free Energies from Data on Coarsening Plus Assessments of Gibbs Free Energies of Mixing in Ni-Base g/g’ Alloys

[O76]18:10

Dan Cai, Lijun Zhang, Yong DuPhase-field simulation of grain growth in anisotropic systems

[O77]18:30

Jennifer M. Ullbrand, Bo Jansson, Ferenc Tasnádi, Lars Hultman, Magnus OdénThe effect of elastic anisotropy on the spinodal decomposition in (Ti,Al)N - a phase field study

[O78]18:50

Denis Shishin, Christopher Bale, Eugene Jak, Sergei A. DecterovThermodynamic database for copper smelting and converting

19:10 Dinner

20:30Poster Session

22:30

Thursday (Afternoon), May 26

16


Friday (Morning), May 27Experiments and databases

ChairsProf. Zi-Kui Liu

Prof. Bo Sundman

[O79]08:30

Rainer Schmid-Fetzer, Joachim Groebner, Artem Kozlov, Milan HamplProgress in magnesium alloy database development

[O80]09:00

Mamoun Medraj, Mohammad Mezbahul-Islam, Elhachmi EssadiqiThe Mg-Cu-Ni-Y quaternary system: thermodynamic modeling coupled with key experiments

[O81]09:20

M Jiang, HX Li, YP Ren, SM HaoExperimental study on the long period ordered (LPO) phase in magnesium alloys

[O82]09:40

Ales Kroupa, Alan Dinsdale, Andrew Watson, Jan Vrestal, Adela Zemanova, Pavel BrozThe COST MP0602 Thermodynamic Database for High-Temperature Lead-free Solders

[O83]10:00

Leszek Zabdyr, Grzegorz GarzelEMF Measurements in the Liquid Ag-Bi-Cu-Sn Lead-free Solder Alloys.

10:20 Coffee-break

ChairsDr. Suzana G. Fries

Prof. Tomás Gómez-Acebo

[O84]10:45

Ursula R. Kattner, Bo Sundman, Mauro Palumbo, Suzana G FriesOpen Calphad - software and databases

[O85]11:15

Bengt HallstedtThermodynamic evaluation of the Ti-Al-C system

[O86]11:35

Zi-Kui Liu, Zhi-Gang Mei, Vidvuds OzolinsLattice stability by ab initio molecular dynamic simulations

[O87]11:55

M Hindler and A. MikulaThermodynamic Properties of the Au-Sb-Sn and Au-Sb system

[O88]12:15

D. Kobertz, M. MüllerExperimental Studies and Re-assessment of the Quasi-binary Systems containing the Sulfates of Sodium, Potassium, and Calcium by Differential Thermal Analysis and X-Ray Diffraction

12:35 Closing session

17


Abstracts: Oral Presentations, May 23 (Monday)

Ab Initio

18


[O1]The Cluster Expansion Method: First Principles or Phenomenology?

J.M. Sanchez

The University of Texas at Austin

The Cluster Expansion (CE) method has been used extensively over the last 25 years to obtain effective cluster interactions (ECIs) that are expected to describe the energy of disordered alloys exhibiting short-range order. Furthermore, these ECIs are extracted from the energies of a relatively small set of ordered compounds calculated using first-principles density functional theory (DFT). Thus, from its inception, the objective and/or promise of the CE has been to provide an important ingredient in the development of a first-principles thermodynamic theory of alloys. In this presentation, we will briefly review a rigorous mathematical formulation of the CE [1] that shows that the cluster basis developed by Sanchez, Ducastelle and Gratias [2] is a multidimensional discrete Fourier transform while the general formalism of Sanchez [3] corresponds to a multidimensional discrete wavelet transform. Weaknesses and strengths of the CE method, as well as its potential role in the quest for a first-principles thermodynamic theory of alloys, will be explored for several cases ranging from a simple pair potential model to energies obtained using DFT.

Key words: Cluster Expansion, disordered alloys, short-range order.

[1] J. M. Sanchez, Phys. Rev. B 81, 224202 (2010). [2] J.M. Sanchez, F. Ducastelle, and D. Gratias, Physica 128A, 334 (1984). [3] J. M. Sanchez, Phys. Rev. B 48, 14013 (1993).

19


[O2]Accuracy and limitations of ab initio approaches in predicting free

energies for binaries and unstable phases

Jörg Neugebauer, Blazej Grabowski, Albert Glensk, and Tilmann Hickel

Max-Planck-Institut für Eisenforschung, Düsseldorf, Germany

In order to extend and improve the algorithms and databases needed for the construction of phase diagrams, additional information on e.g. the volume/pressure dependence of thermodynamic properties, the detailed balance of the various physical excitation mechanisms, and the free energy of unstable phases is crucial. Since an experimental approach to this information is partly not even feasible, the interest in ab initio based methods, in particular density functional theory (DFT), has been in the last few years re-intensified. Recently we have demonstrated that the presently available DFT exchange-correlation functionals are sufficient to predict the temperature dependence of free energies, heat capacities, thermal expansion coefficients and even defect properties of unary fcc metals with an accuracy that often rivals experimental data [1,2,3]. While these first results are very promising, many challenging questions remain. For example: How to compute free energies of instable phases that defy well established concepts based e.g. on the quasiharmonic approximation (due to unphysical imaginary phonon modes) or molecular dynamics? or: Can these methods be extended to chemically more complex alloys and/or to compare several phases on an absolute energy scale? To address these questions, we carefully selected benchmark systems. We have chosen Mg-Si alloys as an example for a binary system and Ca for a system with an unstable phase and a phase transition. Extending our previous approach originally developed for unary systems we were able to compute all relevant free energy contributions such as configurational, electronic, and vibrational contributions. Besides the comparison of the thermal expansion, heat capacity, or the temperature dependent bulk modulus with experimental data, we also compared directly the constant pressure DFT free energies. The results showed over a large temperature range an excellent agreement with CALPHAD data. An extension of the formalism to also include anharmonic contributions also allowed to include unstable phases and to accurately predict the fcc/bcc phase transition of Ca.

[1] B. Grabowski, T. Hickel, and J. Neugebauer, Phys. Rev. B 76, 024309 (2007). [2] B. Grabowski, PhD-Thesis, University Paderborn (2009). [3] B. Grabowski, L. Ismer, T. Hickel, and J. Neugebauer, Phys. Rev. B 79, 134106 (2009); see also the Viewpoint in Physics: G. Grimvall, Physics 2, 28 (2009).

20


[O3]Ab-initio calculation of the bcc order/disorder relations in the Al - Cr - Fe

(Aluminum - Chromium - Iron) system

Helena Maria Petrilli1, Ney Sodré1, Pablo Guillermo Gonzales-Ormeño2, Claudio Geraldo Schon3

1Instituto de Física da Universidade de São Paulo, Brazil 2Universidad Nacional Tecnologica del Cono Sur de Lima, Perú

3Escola Politécnica da Universidade de São Paulo, Brazil

It is widely recognized (e.g. [1]) that Chromium is the most important alloying element used in the development of iron aluminides. It is surprising, therefore, that the order/disorder relations in this system are scarcely studied in the literature. Most published works (e.g. [2,3]) in this system address only the Al-rich corner or the phase relations involving the more complex Al-rich intermetallic phases, leaving the large bcc field empty (although they recognize that B2 order occurs). This lack of experimental and theoretical information is probably caused by extreme experimental difficulties (e.g. the similarity between the atomic numbers of Fe and Cr, which limit the usage of x-ray diffraction data) as well as theoretical difficulties due to the complex magnetic ordering in the Fe and Cr-bearing compounds. This work presents, to the knowledge of the authors, the first ab-initio thermodynamic description of the bcc Al - Cr- Fe system. The calculations are performed in the framework of the so-called cluster expansion method, by combining Full Potential, Linear Augmented Plane Wave (FP-LAPW) electronic structure calculations and the Cluster Variation Method (CVM) in the irregular tetrahedron approximation.

Key words: Iron aluminides; alloying, Full Potential - Linear Augmented Wave (FP-LAPW), Cluster Variation Method (CVM).

[1] - R. Balasubramaniam, On the role of chromium in minimizing room temperature hydrogen embrittlement in iron aluminides, Scripta Mater. 34 (1996) pp. 127 - 133. [2] - M. Palm, The Al - Cr - Fe system - phases and phase equilibria in the Al-rich corner, J. Alloys Comp. 2

21


[O4]First Principles Phase Diagram Calculations for the systems:

SiC-AlN; SiC-GaN; SiC-InN; and ZrO_X (0 < X < 1)

Benjamin Burton1, A. van de Walle2

1NIST 2Caltech

The ATAT-package [1] was used to perform cluster-expansion method first principles phase diagram (FPPD) calculations for the wurtzite-structure quasibinary systems SiC-AlN, SiC-GaN and SiC-InN. In SiC-AlN, planewave pseudopotential formation-energy calculations predict low-energy metastable states with formation energies, Delta-E_f ~ 0.04 eV/mole (mol = one cation + one anion). The crystal structures of these states are all of the form (SiC)_m(AlN)_n(SiC)_o(AlN)_p...(m,n,o,p integers), where (SiC)_m indicates m SiC-diatomic-layers _|_ to the hexagonal c-axis and similarly for (AlN)_n,(SiC)_o and (AlN)_p. The presence of low-energy layer-structure metastable states helps to explain why one can synthesize (SiC)_{1-X}AlN)_X films, or single crystals, with any value of X, in spite of the apparently strong tendency toward immiscibility. In SiC-GaN, ordered structures are predicted at X=1/4, 1/2, and 3/4 (Pm, Pmn2_1 and Pm, respectively). In SiC-InN, one Cmc2_1 ordered phase is predicted at X=1/2.

Key words: First Principles Phase Diagram Calculations; SiC-AlN; SiC-GaN; SiC-InN; and ZrO_X, Zr-suboxides.

[1] A. van de Walle and G. Ceder, Journal of Phase Equilibria, V23 p. 348 (2002).

22


[O5]Ab initio modeling in the Mg-Si system

Gilles Hug1, Philippe Jund2, Romain Viennois2, Catherine Colinet2, Jean-Claude Tédenac2

1LEM ONERA-CNRS 2CNRS, Université de Montpellier

Mg2Si is a promising material for energy production from thermoelectric effect. In order to control the processing of such materials, an accurate knowledge of the Mg-Si phase diagram and the behavior of the different intrinsic doping defects in required. The Mg-Si system is relatively simple and contains only one defined compound of the cubic anti-fluorite structure (CaF2 prototype) at the Mg2Si stochiometry. However, some discrepancies still remain in the literature between the experimental formation enthalpy of Mg2Si and calculated ones. In particular the existence or not of a high pressure Lave phase in not well established. The formation energy of point defects such as vacancies, interstitials and antisite are also scarcely determined. We present a theoretical study of the relative stability under pressure of the anti-fluorite structure as compared to four other possible structures (Cu2Mg, MgZn2, Ni2In, MgNi2 prototypes). Phonon calculations are performed in selected cases in order to study the temperature relative stability as well. Finally, the formation energy of the different intrinsic defects has been determined. These calculations have been done using several well-established ab initio methods including pseudo-potential plane wave, full potential plane waves and full potential local orbitals associated with different exchange and correlation potentials.

Key words: Silicides ; elastic properties ;electronic structure of metals and alloys ; thermal properties; ab-initio calculations.

23


[O6]Progress of theoretical study of alloy phase equilibria based on

Cluster Variation Method

Tetsuo Mohri

Hokkaido University

Cluster Variation Method (CVM) is one of the most reliable theoretical tools for studying alloy phase equilibria. The conventional CVM, however, does not incorporate local lattice distortion effects into the free energy and, therefore, the calculated phases are still in the excited state. One way to circumvent such inconvenience is to employ Continuous Displacement Cluster Variation Method (CDCVM). Recently, the author extended CDCVM calculations from two-dimensional square lattice to fcc lattice. In the present talk, review of theoretical calculations of phase equilibria based on CVM is provided.

Key words: Cluster Variation Method, Continuous Displacement Cluster Variation Method, First-principles calculation.

24


[O7]Laves phases in the Hf-V and V-Zr systems: Stability analysis using ab initio

data and phase diagrams

Jan Vřesťál, Jana Pavlů

Masaryk University, Fac. Sci., Department Chemistry, Kotlářská 2, 611 37 Brno, Czech Republic

Systems Hf-V and V-Zr are well known systems where transformation from non-Laves phase to Laves phase exists by increasing temperature [1-4]. The transformation from body-centered tetragonal or orthorhombic HfV2 or rhombohedral ZrV2 structure to cubic C15 Laves phase at about 100 to 115 K was described experimentally more in detail in [2-4]. Analysis of this anomaly using ab initio calculated total energies is presented and consequences of this analysis for phase diagram of both systems are discussed.

Financial support of Czech Science Foundation by grant No. P108/10/1908 and of Ministry of Education of the Czech Republic No. MSM0021622410 are gratefully acknowledged.

Key words: Laves phases, Hf-V system, V-Zr system, ab initio calculations.

[1] F. Stein, M. Palm, G. Sauthof: Intermetallics 13 (2005) 1056-1074. [2] Y. Zhao, F. Chu, R.B. von Dreele, Q. Zhu: Acta Crystallographica B 56 (2000) 601. [3] F.R. Drymiotis et al.: Phys. Rev. B72 (2005) 024543. [4] O. Rapp, G. Benediktsson: Phys. Lett. A 74 (197).

25


[O8]Energetics and magnetism of Mo-based sigma phases

J. Pavlů 1,2, J. Vřešťál 1,2, M. Šob 1,2

1 Masaryk University Brno, Czech Republic 2 Institute of Physics of Materials, ASCR, Brno, Czech Republic

The overview of ab initio calculated energies of formation of the sigma phases in Co-Mo, Cr-Mo and Fe-Mo systems will be given. These energies were evaluated with respect to the structures of pure constituents which are stable at standard ambient temperature and pressure (i.e. ferromagnetic hcp Co, antiferromagnetic bcc Cr, ferromagnetic bcc Fe, nonmagnetic bcc Mo) and using various methods. [1-5] These total energy differences are compared with available data. The magnetism of various configurations was also investigated and the stabilizing effect of magnetic ordering in Co-Mo and Fe-Mo was proved. The magnetic moments per atom and their relation to the composition and atomic site will be discussed.

Acknowledgements: This research was supported by the Grant Agency of the Czech Republic (Project no. P108/10/1908), Ministry of Education of Czech Republic (Project no. MSM0021622410) and Academy of Sciences of the Czech Republic (Project no. AV0Z20410507). The access to the computing facilities of the MetaCenter of the Masaryk University, Brno is acknowledged.

[1] G. Krier, O. Jepsen, A. Burkhardt, and O.K. Andersen, computer code TB-LMTO-ASA version 4.6, Max-Planck-Institut für Festkörperforschung, Stuttgart, 1994. [2] P. Blaha, K. Schwarz, and J. Luitz, computer code WIEN97, Vienna University of Technology, 1997 [improved and updated Unix version of the original copyrighted WIEN code, which was published by P. Blaha, K. Schwarz, P. Sorantin, and S.B. Trickey, Comput. Phys. Commun. 59 (1990) 399]. [3] P. Blaha, K. Schwarz, G.K.H. Madsen, D. Kvasnicka, and J. Luitz, WIEN2k, An Augmented Plane Wave Plus Local Orbitals Program for Calculating Crystal Properties (Karlheinz Schwarz, Technische UniversitätWien, Austria, 2001). [4] G. Kresse and J. Furthmüller, Comp. Mat. Sci. 6, 15 (1996). [5] G. Kresse and J. Furthmüller, Phys. Rev. B 54, 11169 (1996).

26


[O9]Thermodynamic properties of M-In-Sn (M = Cu, Ni) intermetallics: Ab initio

database and systematics

Susana Ramos de Debiaggi1, Críspulo Deluque Toro1, Gabriela F. Cabeza2, Armando Fernández Guillermet3

1Dpto. de Física, Facultad de Ingeniería, Universidad Nacional del Comahue, Neuquén, Argentina

2Dpto. de Física, Universidad Nacional del Sur, Bahía Blanca, Argentina 3Centro Atómico Bariloche e Instituto Balseiro, (8400) Bariloche, Argentina

The phase stability properties of the Cu-In-Sn and Ni-In-Sn intermetallic phases (IPs) are currently a subject of attention in connection with the development of lead-free soldering alloys. In particular, considerable efforts have been devoted to the development of predictive approaches to the thermodynamics of binary and higher order IPs of actual and potential technological relevance for the lead-free diffusion soldering methods [1,2]. The theme of the present work is the use of ab initio methods for developing a database with theoretical information of various IPs of interest in connection with the thermodynamic analysis of the Cu-In-Sn, Ni-In-Sn and their binary subsystems. Specifically, systematic ab initio density-functional-theory calculations have been performed to establish trends in the 0 K energies of formation (EOF) of several IPs which are stable in the Cu-In, Cu-Sn, Ni-In and Ni-Sn binaries. We used the VASP code [3] with the projector augmented wave potentials and the generalized gradient approximation for the exchange and correlation functions. In this way, various stable, metastable or hypothetical compounds involved in the Compound-Energy Model (CEM) [4] treatment of these binary and higher-order systems are studied. The present contribution includes a discussion of the trends in the EOF vs. composition [5,6]. In addition, new correlations for the EOF are presented which open up the possibility of using these results in CALPHAD optimizations using the CEM.

Key words: Ab initio calculations; transition metals and alloys; Cu-In and Cu-Sn intermetallic phases; lead-free soldering alloys; Compound-Energy Model.

[1] G. Ghosh, M. Asta, J. Mater. Res. 20 (2005) 3102. [2] G. Ghosh, Metallurgical and Materials Transactions 40A, (2009) 4. [3] G. Kresse, J. Furthmüller, Comput. Mater. Sci. 6 (1996) 15. [4] M. Hillert, J.Alloys Compd. 320 (2001) 161. [5] S. Ramos de Debiaggi et al., J. Alloys Compd. (2011), in press. [6] S. Ramos de Debiaggi, G.F. Cabeza, A. Fernández Guillermet, submitted to Physica B.

27


[O10]Ternary Phase Diagrams for Plastic Crystal Energy Storage Materials -

Computational and Experimental Approach

Anjali Talekar, Dhanesh Chandra

University of Nevada, Reno

Ternary phase diagrams of PE-AMPL-TRIS, PE-PG-TRIS and PG-NPG-TRIS ‘Plastic Crystals’ are important for low and high temperature passive energy storage. Based on our previous work we have found that there are low temperature transitions near 273K to 300K, which were not observed in the binaries. In order to predict phase transitions by adding a third component to the binaries, ternary phase diagrams are important. We will present the above ternary phase diagrams using CALPHAD methodology. Low temperature, tetragonal, monoclinic, and orthorhombic phases of these organic compounds transform to orientationally disordered high temperature FCC or BCC phases. The low temperature phases are assumed to be ideal based on the relatively small interaction between them, whereas the high temperature phases are assumed to be subregular. The excess molar Gibbs energies for the binaries involved are fitted using Redlich-Kister polynomial built into the TCC software. We are also performing low and high temperature in-situ x-ray diffraction and differential scanning calorimetry on these ternaries to determine experimental phase diagram of one system for corroborating with the computational work. PE: Pentaerythritol C5H12O4, PG: Pentaglycerine- C5H12O3, NPG: Neopentylglycol-C5H12O2, AMPL: 2-amino-2-methyl-1,3-propanediol- C4H11NO2, and TRIS: Tris(hydroxymethyl) aminomethane-C4H11NO3 Program funded by Intel Corporation

Key words: ‘Plastic’ crystals; ternary phase diagrams; CALPHAD.

28


[O11]Configurational thermodynamics of multicomponent complex

alloy systems from first-principles theory.

Igor Abrikosov, Björn Alling, Marcus Ekholm, Hans Lind, Ferenc Tasnadi

Linköping University

We review recent advances in first-principles theory of alloy thermodynamics [1] and illustrate its predictive power in studies of decomposition behavior of multicomponent nitride alloys for hard coating applications [2], as well as in studies of influence of magnetic excitations on chemical order-disorder transition in Fe-Ni permalloy [3]. To model the phase diagram of cubic Ti1−xAlxN we develop a unified cluster expansion approach. In our scheme the alloy Hamiltonian is expanded in terms of concentration and volume dependent effective cluster interactions, where the chemical fixed-lattice and local lattice relaxation terms are incorporated. Based on the obtained results, we propose a design route for the next generation of nitride alloys via a concept of multicomponent alloying based on self-organization on the nanoscale via a formation of metastable intermediate products of the spinodal decomposition. We show that in case of TiCrAlN alloys it leads to considerable improvement of thermal stability of thin films for hard coating applications [2]. For random Ni-rich Fe-Ni alloys, we demonstrate from ab initio calculations that deviations of the global magnetic state from ideal ferromagnetic order due to temperature induced magnetization reduction have a crucial effect on the chemical transition temperature. We propose a scheme where the magnetic state is described by partially disordered local magnetic moments, which allows us to reproduce the transition temperature in good agreement with experimental data [3].

Key words: configurational thermodynamics, first principles, TiAlN, TiCrAlN, Fe-Ni permalloy.

[1] A. V. Ruban and I. A. Abrikosov, Rep. Prog. Phys. 71, 046501 (2008). [2] B. Alling, A. V. Ruban, A. Karimi, L. Hultman, and I. A. Abrikosov, Phys. Rev. B (submitted, available as arXiv:1012.3120v1), H. Lind, R. Forsén, B. Alling, N. Ghafoor, F. Tasnadi, M.P. Johansson, I. A. Abrikosov, and M. Odén, in manuscript. [3] M. Ekholm, H. Zapolsky, A. V. Ruban, I. Vernyhora, D. Ledue, and I. A. Abrikosov, Phys. Rev. Lett. 105, 167208 (2010).

29


[O12]First principles calculations of stacking fault energy of P doped Si crystal

S.R.Nishitani1, K. Togase1, Y. Ohno2, Y. Tokumoto2, and I. Yonenaga2

1 Department of Information, Kwansei Gakuin University, Gakuen 2-1, Sanda, 669-1337 Japan 2 Institute for Materials Research, Tohoku University, Katahira 2-1-1,

Aoba-ku, Sendai, 980-8577 Japan

Very recently, the authors have reported that the variation in stacking fault energy with annealing at 1173 K in Czochralski-grown silicon crystals heavily doped with n- or p-type dopant atoms[1]. In n-type crystals, the stacking fault energy decreased with increasing annealing time. As the concentration of dopant atoms increases, the stacking fault energy decreases. On the other hand, the energy was unchanged during annealing in p-type and non-doped crystals. These results imply that n-type dopant atoms segregate nearby a stacking fault, via their thermal migration. In this research, we investigated that the dopant effect of phosphorus is confirmed by the first principles calculations. The slab model including a stacking fault has been constructed, and been calculated by the VASP(Vienna Ab-initio Simulation Package) code with the cut-off energy of 1000eV and PAW potentials. One P atom is putted in the model and compare the energies and interatomic distances. Fig. 1 shows the site dependency of the energy. The left pannel shows the schematic model of the slab, where the c and h represent the cubic and hexagonal stacking sequences, respectively. Thus the stacking fault are located at the site numbers of 9-10 and 11-12. In this case, because of the small unit size of slab, the replacement of one atom means that the atoms in a whole layer are replaced. The structure energies of P added Si slab show the relative stable when the P atoms are located around the sacking fault. This result strongly suggests that the lowering of the stacking fault energy is due to the P enrichment nearby the stacking fault during the annealing.

Fig.1 Schematic slab model and the energy dependency on site.

[1] Y. Ohno, T. Taishi, Y. Tokumoto, and I. Yonenaga, J. Appl. Phys. 108(2010), 073514.

30


[O13]Computational and experimental investigations of defects

and stability of (La1-xCax)FeO3-δ perovskites

Sung Hoon Lee, Zi-Kui Liu

The Pennsylvania State University

(La1-xCax)FeO3-δ perovskites have a wide range of applications such as gas separation membranes and cathodes in solid oxide fuel cells. Its performances are dictated by defect structures under service conditions, and in the present work, the defect structures and energetics of (LaxCa1-x)FeO3-δ are studied. Energetics of various defects are investigated by first-principles calculations based on density functional theory to understand their relative dominance. The interactions of multi-component and multiple-defects are modeled by the CALPHAD method using the thermochemical data from first-principles calculations and oxygen nonstoichiometry and phase equilibrium data from experimental investigations in the literature and obtained in the present work. Ionic sublattice model is used to model the perovskite phase, and the calculated phase diagrams are in good agreement with experimentally reported phase equilibrium data. Based on the developed models, the oxygen vacancy concentration as a function of partial pressure of oxygen, temperature, and calcium concentration are obtained.

Key words: Perovskite, defect chemistry, Compound energy formalism, CALPHAD, first-principles calculations, ionic sublattice.

31


[O14]Phase stability and thermomechanical properties of

LSCF and BSCF perovskites

Torsten Markus1, Jens Emmerlich2, Denis Music2, Li Yang3

1Forschungszentrum Jülich GmbH, IEK-2, D-52425 Jülich, Germany 2Materials Chemistry, RWTH Aachen University, D-52074 Aachen, Germany

3Forschungszentrum Jülich GmbH, IEK-2, D-52425 Jülich, Germany

Active materials applicable as oxygen separation membranes have to exhibit both high ionic and electronic conductivity. Two of the promising materials are La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) and Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF). The aim of the presented study is to calculate the thermodynamic stabilities and thermo chemical properties of LSCF and BSCF such as phase transition temperatures, stabilities, heat capacities, based on ab initio calculations. With the ab initio stability data in hand, thermo chemical software packages will be used to estimate the stability of LSCF and BSCF against chemically aggressive agents. Furthermore, the aim is to calculate elastic constants for the most relevant structural modifications of LSCF and BSCF. To verify our modeling activities, experimental studies using Differential Scanning Calorimetry (DSC) and Differential Thermal Analysis combined with thermo gravimetric measurements (DTA/ TG) were conducted.

Key words: Ab initio perowskites experimental.

32


[O15]Formation and migration of native defects in complex hydrides

Jianchuan Wang1, Yong Du1,*, Honghui Xu1, Lixian Sun2, Zi-Kui Liu3

1 State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, PR China

2 Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, People’s Republic of China

3 Materials Science and Engineering, Pennsylvania State University, University Park, Pennsylvania 16802, USA

*E-mail: [email protected]

Among various solid state storage materials, complex hydrides, which are referred to alkali and alkaline-earth metal salts of [NH2]¯, [BH4]¯ and [AlH4]¯, have received considerable attention due to their high volumetric and gravimetric density. The major problem associated with the dehydrogenation/hydrogenation of complex hydrides is the slow kinetics. Hydrogen reactions in complex hydrides are generally more complicated than those in conventional metal hydrides since both hydrogen and other constituent elements are involved at various steps of the reactions. Understanding the microscopic mechanism of the hydrogenation and dehydrogenation processes is the key to enhance the kinetics and decrease the decomposition temperature. We have studied defect aspects in Na3AlH6 (the intermediate compound for decomposition of NaAlH4) and LiNH2 (lithium amide) by first-principles calculations based on density functional theory in the generalized gradient approximation. Defect induced local atomic structures, formation energies of defects and migration of dominant defects were investigated. We find that for the above two hydrides energetically favorable defects are in charged states other than in neutral states. For Na3AlH6, we characterized several migration scenarios for all types of H vacancy. Our work demonstrates that the barrier for local diffusion is lower than that for corresponding nonlocal diffusion and H transport in Na3AlH6 is dominated by mobility of positively charged H vacancies. For LiNH2, our investigations show that both Hi

+ and Hi0 correspond to the formation

on an NH3 molecular. The energetically favorable H and Li-related defects are VH¯, Hi+, Hi¯, VLi¯, and ILi

+. Single positively charged NH2 vacancy (VNH2¯) has the lowest formation energy in N-related defects and the formation energies of N interstitials are substantially higher. The migration barrier for VH¯ is relatively high (0.88 eV), whereas charged H interstitial has moderate diffusion barriers (0.40 eV for Hi¯ and 0.46 eV for Hi

+). The Li-related defects are predicted to be diffusion readily with a migration barrier of just 0.20 eV for VLi¯ and 0.38 eV for ILi

+. The predicted activation energies for self-diffusion show that the formation of H interstitial is the bottleneck for H transport. and Li-related defects are the predominant diffusion species in LiNH2.

Acknowledgements The financial support from the National Natural Science Foundation of China (Grant Nos. 20833009, 50721003 and 50831007) is greatly acknowledged.

[1] J.C. Wang and Y. Du et al., Int. J. Hydrogen Energy, 35, 609-613 (2009). [2] J.C. Wang and Y. Du et al., Appl. Phys. Lett., 95, 111910/1-3 (2009).

33


[O16]A comparative analysis of the effect of particle pinning and solute segregation on

the inhibition of grain boundary movement

Byeong-Joo Lee1, Je-Wook Jang1, Kyu-Seok Han2, Chan-Hee Han2

1Pohang University of Science and Technology (POSTECH) 2POSCO Technical Research Laboratories, POSCO

Microstructural evolution has a decisive effect on properties of polycrystalline materials. Inhibition of grain boundary movement is often an important process to control the microstructure. Particle pinning has long been used as a means to inhibit the grain boundary movement. Even though a similar inhibition is expected from the segregation of solute atoms on grain boundaries, its effect is not quantitatively known. The purpose of the present study is to quantitatively evaluate the possibility of the use of grain boundary segregation as an inhibitor of grain boundary movement, by comparing the pinning pressure from AlN precipitation and Sn segregation in bcc Fe using atomistic simulation techniques (molecular dynamics and Monte Carlo simulation). The way of evaluating grain boundary mobility [1], molecular dynamics simulation to estimate the pinning pressure, interatomic potentials [2] for the atomistic approaches and the way of extrapolating simulation results to real scale will be presented as well as the final results, the relative ability between AlN pinning and Sn segregation for the inhibition of grain boundary movement in bcc Fe.

Key words: particle pinning, solute segregation, grain boundary mobility, atomistic simulation.

[1] K.G.F. Janssens, D. Olmsted, E.A., Holm, S.M., Foiles, S.J. Plimpton and P.M. Derlet, Nature Materials 5, 124-127 (2006). [2] B.-J. Lee, W.-S. Ko, H.-K. Kim, E.-H. Kim, CALPHAD 34, 510-522 (2010).

34


[O17]Actinide Alloys and their Challenges

Patrice E. A. Turchi, Alexander I. Landa

Lawrence Livermore National Laboratory

The current interest in a better usage of actinide-based mixtures in nuclear reactors and the applicability of nuclear fuels in hybrid fusion-fission systems raises challenging questions on the increasing role of minor actinides and fission products and gases on fuel stability and performance. Nuclear materials under extreme conditions of temperature and irradiation with a temporal evolution of materials chemistry require a fundamental knowledge that must feed into physics-based fuel performance codes to build in predictability and to tackle the question of fuel behavior under normal and also accidental operating conditions. Hence, the prediction of phase stability trends and phase diagrams of multi-component complex actinide-based alloys is undoubtedly the Holy Grail of alloy physics and materials properties simulations. In this presentation, we will first discuss some of the most promising fuel forms that are currently considered for advanced nuclear reactors and hybrid fusion-fission engines. Then, we will show that despite the urgent need for more experimental work, the CALPHAD methodology, combined with appropriate first-principles electronic structure calculations, is a powerful tool to investigate and predict the thermodynamic properties of actinide-based alloys. We will focus on three different themes: the Pu solubility challenge in nuclear molten salts, the Pd attack in nuclear TRISO particles, and the possible improvement in metallic fuels to minimize the so-called site-redistribution. Ultimately, since experiments on actinide alloys are costly and challenging, we will show that despite their own limitations ab initio results may provide useful guidance for well-chosen experiments that can lead to full validation and verification of the thermodynamic driving force that is required for subsequent work on materials performance.

Key words: Phase diagrams, ab initio calculations, thermodynamic modelling, materials for energy, actinide alloys, nuclear materials.

This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

35


[O18]Structural stability of the ternary compounds Mo5SiB2 and Nb5SiB2

Catherine Colinet1, Jean-Claude Tedenac2

1Science et Ingénierie des Matériaux et Procédés, Grenoble INP, UJF, CNRS, 38402 Saint Martin D’Heres Cedex France

2Institut de Chimie Moléculaire et des Matériaux I.C.G., UMR-CNRS 5253, Université Montpellier II, Place E. Bataillon , 34095 Montpellier Cedex 5, France

Experimental investigations in Mo-Si-B [1, 2] and Nb-Si-B [3] systems show the existence of the ternary phases Mo5SiB2 and Nb5SiB2 crystallizing in the B3Cr5-prototype structure. In the present work, we have performed ab-initio calculations of lattice parameters and energies of formation for the Mo5SiB2 and Nb5SiB2 ternary compounds by considering three possible competiting structure types: Mn5Si3-prototype (D88), W5Si3-prototype (D8m or T1) or B3Cr5-prototype (D81 or T2). These calculations have been carried out using the Vienna ab initio simulation package (VASP) [4], making use of potentials constructed by the projector-augmented waves (PAW) technique [5, 6]. For the GGA exchange correlation function, the Perdew-Wang (PW91) [7, 8] or the Perdew, Burke and Ernzerhof (PBE) [9] parameterizations are employed. We show that the Mo5SiB2 and Nb5SiB2 ternary compounds are effectively stable in the B3Cr5-prototype structure. The calculated lattice parameters as well as the internal parameters are in good agreement with the experimental determinations. Both electronic and size effects allow to explain the stability of the Mo5SiB2 and Nb5SiB2 ternary compounds in the B3Cr5-prototype structure.

Key words: Ab-initio, Mo5SiB2, Nb5SiB2.

[1] J.H. Schneibel, C.T. Liu, L. Heatherly, L. Kramer, Scr. Mater. 38 (1998) 1169. [2] C. A. Nunes, R. Sakidja, Z. Dong, J. H. Perepezko, Intermetallics 8 (2000) 327. [3] D.N.P. Junior, C.A. Nunes, G.C. Coelho, F. Ferreira, Intermetallics, 11 (2003) 251. [4] G. Kresse and J. Furthmüller, Comp. Mater. Sci. 6 (1996) 15; Phys. Rev. B 54 (1996) 11169. [5] P. E. Blöchl, Phys. Rev. B 50 (1994) 17953. [6] G. Kresse and D. Joubert, Phys. Rev. B 59 (1998) 1758. [7] J. P. Perdew and Y. Wang, Phys. Rev. B. 45 (1992) 13244. [8] J.P. Perdew, J.A. Chevary, S.H. Vosko, K.A. Jackson, M.R. Pederson, D.J. Singh, C. Fiolhais, Phys. Rev. B 46, 6671 (1992). [9] J. Perdew, K. Burke, M. Ernzerhof, Phys. Rev. Lett., 77 (1996) 3865.

36


[O19]Ab-initio calculations of Er-H compounds: application to the

modelling of the phase diagram

Jean-Marc Joubert1, Aurore Mascaro2, Jean-Claude Crivello1, Caroline Toffolon-Masclet2

1CMTR, ICMPE, CNRS 2CEA, DEN, DMN/SRMA/LA2M

Metal-hydrogen systems are interesting from both the fundamental and application point of views. Up to now, not so many systems have been studied by ab initio calculations and/or modelled by the Calphad technique and it is a growing field of research. In the present work, the reaction of hydrogen with erbium has been studied by first-principles calculations. The enthalpies of formation of the compounds Er, ErH, ErH2 and ErH3 generated by ordered insertion of hydrogen atoms in the tetrahedral and octahedral (or triangular) sites of the fcc and hcp structures have been calculated. The results of the calculations are consistent with the experimental observation of the sequence Er (hcp) -> ErH2 (fcc) -> ErH3 (hcp), qualitatively, and with the measured enthalpies of formation, quantitatively. These results have been used to describe the stable and metastable end-members generated by the compound energy formalism for the two phases and a description of the phase diagram assessed by the Calphad technique will be proposed.

Key words: Ab initio, metal hydrides, Calphad assessment, Er-H.

37


[O20]Calculating heats of formation using DFT: guidelines for the

study of TCP phases

J.-C. Crivello1, M. Palumbo2, T. Hammerschmidt2, S.G. Fries2, J.-M. Joubert1

1CMTR-ICMPE-CNRS, France 2ICAMS-STKS, Germany

Calculating heat of formation using density functional theory (DFT) has been in common usage for several decades, in particular in conjunction with the Calphad method. In fact, Calphad thermodynamic modeling requires a complete energetic description of a system, which could be limited by experimental works alone. To compensate for the lack of information, DFT calculations can provide formation enthalpies at 0K of any ordered compounds, even in metastable states. The aim of this work is to present our experience of first-principles calculations to estimate the heat of formation of compounds formed at 0K, with a focus on the complex topologically-close packed phases (TCP). Taking the chi and sigma phases as examples, we present calculations of all ordered configurations for several rhenium-based systems. From these results, we discuss the influence on the converged energy (i) of the basic pseudo-potential parameters, (ii) of the exchange-correlation functional LDA and GGA (PW91 or PBE), (iii) of the magnetic contribution, and (iv) of the number of valence electrons considered with different pseudo-potentials. In each case, we pay attention to the validity of ab initio results in comparison with the experimental data available: lattice parameters, internal coordinates, site occupancies and formation enthalpies.

Key words: DFT, ab initio, TCP phases, sigma, chi, Re-based system, intermetallics.

38


[O21]Bridging ab initio and CALPHAD by a robust magnetic model

Wei Xiong1, Pavel Korzhavyi1, Qing Chen2, Malin Selleby1

1Department of Materials Science and Engineering, KTH (Royal Institute of Technology) 2Thermo-Calc AB, Norra Stationsgatan 93, SE-113 64 Stockholm, Sweden

The ab initio and CALPHAD methods have developed rapidly during the last decades as the main tools for materials design. However, both methods have their own limitations. CALPHAD shows its power above 300 K while ab initio usually does at 0 K. Therefore, extending the CALPHAD method down to temperatures below 300 K is an interesting topic. In this work, the state-of-the-art magnetic model of the CALPHAD approach is reviewed. It is found that, in order to accurately predict magnetic contributions to the Gibbs energy of alloys, the Inden-Hillert-Jarl (IMJ) model [1, 2] needs to be improved. Firstly, the relation between magnetic moment and magnetic entropy is elucidated to assure the correct estimation of the magnetic entropy. Secondly, a new function is adopted for describing the Curie/Néel temperature and magnetic moment in order to evaluate the magnetic ordering energy due to the transformation between different magnetic states. The Fe-Cr-Ni system is studied to illustrate the advantages of the present model. The model-predicted magnetic contributions are distinctly different using the IMJ model and the present one. The present work demonstrates a way to improve the thermodynamic descriptions at low temperatures by adopting the modified magnetic model and the new generation of lattice stability [3].

This work was performed within the VINN Excellence Center Hero-m, financed by VINNOVA, the Swedish Government Agency of Innovation Systems, Swedish Industry and KTH.

Key words: CALPHAD, Magnetic model, Low temperature thermodynamics, Ab initio.

[1] Inden G. In: Proc CALPHAD, V. Max Planck Institut fuer Eisenforschung, Duesseldorf; 1976. p. 1. [2] Hillert M, Jarl M. CALPHAD 1978;2:227. [3] Chen Q, Sundman B. J Phase Equilib 2001;22:631.

39


Abstracts: Oral Presentations, May 24 (Tuesday)

The CALPHAD Method, and Assessments

40


[O22]Calphad – what did we hope for, what did we get – where do we go?

John Ågren

Dept of Materials Science and Engineering Royal Institute of Technology SE-100 44 Stockholm, SWEDEN

In the early 80:ies the Calphad technique started to spread outside the Calphad community, which was quite small at that time and had a hard core of less than 50 individuals. Today the technique has become a standard scientific and engineering tool among other tools that are used to solve various problems. In the early 70:ies many scientists were inspired by the pioneering work of Larry Kaufman and of Mats Hillert which so far had proceeded quite independently. Thanks to the newly launched Calphad conferences and the European efforts within SGTE an intensive international collaboration started. At that time the visions were clear and simple; once general softwares and databases were available almost any thermodynamic calculation would be possible. In this talk the initial visions will be analyzed. Soon unforeseen problems related to the compilation of databases and the deficiencies of the softwares lead to a modification of the visions. On the other hand, it was perhaps unexpected that Calphad could be applied more or less directly in industrial engineering which led to new requirements. The use of Calphad as a cornerstone in other types of simulations became evident. For some years the practical applicability led to commercial values and divergence of the databases. In contrast to the original vision of the single unified database several high-precision special purpose databases became commercially available. When we now meet the future it may come as a surprise that it is the industrial applications that call for a new generation of high-precision databases based on much more fundamental science.

41


[O23]Reassessment of the thermodynamic description of the Fe-C system

Reza Naraghi, Malin Selleby

KTH (Royal Institute of Technology)

A new thermodynamic assessment of the Fe-C system is performed based on the new more physically accurate descriptions of iron, carbon and cementite [1, 2]. The metastable Fe5C2-Hägg and Fe2C-epsilon carbides are included. A four-sublattice model is also developed to describe thermodynamic properties of body centered tetragonal (bct) martensite as an ordered form of the bcc phase. The proposed model can describe the order-disorder transformation and the spinodal decomposition in Fe-C martensite. Using the proposed model the effect of ordering of the stability of martensite is evaluated and compared with experimental data and previous theoretical treatments.

Key words: Thermodynamic modelling; Fe-C system; Martensite; Zener ordering.

[1] Q. Chen and B. Sundman, J of Phase Equilibria, 22 (6) (2001) 631-644. [2] B. Hallstedt, D. Djurovic, J. von Appen, R. Dronskowski, A. Dick, F. Körmann, T. Hickel, and J. Neugebauer, CALPHAD 34 (1) (2010) 129-133.

42


[O24]Ternary Phase Diagram of Li-N-H Complex Hydrides for

Hydrogen Storage Systems

D. Chandra1,*, A. Talekar1, J. Lamb1,W-M Chien1, D. Phanon2, Nicolas Penin2, Radovan Černý2, Klaus Yvon2, J-C Crivello3, M. Latroche3, and M. Gupta4

1 University of Nevada, Reno, Nevada 89557 USA 2University of Geneva, 24 quai Ernest-Ansermet, CH-1211 Geneva 4, Switzerland

3 ICMPE, UMR 7182, CNRS, 2-8 rue H. Dunant, 94320 Thiais, France 4TPCHO, Bâtiment 415, Université Paris Sud, 91405 Orsay, France

*e-mail : [email protected]

Light-weight complex hydrides with high hydrogen capacity are becoming important for vehicular applications. The pioneering work of Chen et al. [1] led to discovery of about 10 wt.% hydrogen using amide-imide system, but the capacity decreases as function of cycling to ~3 wt%H. Several other investigations [2-8] led to a better understanding of the system. We present our work on Li3N (under the USDOE’s Metal Hydride Center of Excellence program), Li amide-imide, in which we detected new phases during hydrogenation of the Li3N compound. The understanding of the phase stability was mainly derived from thermodynamic calculations of the Li-N-H ternary systems at different temperatures and pressures by using the FACT program. These calculations explained the stability of phases obtained experimentally. Hydriding of Li3N (starting compound) yielded a Li coordinated (interstitial type) Li4NH compound formed at low hydrogen pressures (~0.0003 MPa), Li2NH (~0.0005 MPa), a new phase @~0.02 MPa Li1.5NH1.5, and LiNH2 (~0.1 MPa). Calculated ternary phase diagrams predicted reaction pathways and also suggested as to why there were losses in hydrogen capacity. An important observation is that the addition of N2 to hydrogen gas improved the reversible hydrogen capacity in this system. We developed Li-N-H complex hydrides that use 80/20 H2/N2 mixtures that show significant enhancement of the reversible capacity as compared to cycling without nitrogen additives. We attribute this enhancement to the reaction of nitrogen with liquid lithium during cycling. The Gibbs free energy of formation of Li3N (∆Go = -98.7 kJ/mol) is more negative than that of LiH (∆Go = -50.3 kJ/mol). Based on the computations, we propose that the mitigation of hydrogen capacity losses is due to the destabilization of the LiH phase that tends to accumulate during cycling. We will present calculated ternary phase diagrams, experimental and calculated thermodynamic, neutron and x-ray diffraction results and structure electronic by DFT calculations.

[1] P. Chen, Z. Xiong, J. Luo, J. Lin, K. Tan, Nature 21 (2002) 302. [2] F.E. Pinkerton, J. Alloys Compd. 400 (2005) 76. [3] T. Ichikawa, N. Hanada, S. Isobe, H.Y. Leng, H. Fujii, J. Phys. Chem. B 108 (2004) 7887. [4] M.P. Balogh, C.Y. Jones, J.F. Herbst, L.G. Hector Jr., M. Kundrat, J. Alloys Compd. 420 (2006) 326. [5] E. Weidner, D. Bull, I. Shabalin, S. Keens, M. Telling, and K. Ross, Chem. Phys. Lett. 444 (2007) 76. [6] W. I. F. David, M. O. Jones, D. H. Gregory, C. M. Jewell, S. R. Johnson, A. Walton, and P. P. Edwards, J. Am. Chem. Soc. 129 (2007) 1594. [7] F. Zhang, Y. Wang, and M.Y. Chou, Physical Reviews B 82 (2010) 094112. [8] J. C. Crivello, M. Gupta, M. Latroche and D. Chandra, Physical Reviews B 81 (2010) 104113.

43


[O25]Thermodynamic Assessment of V2O3-TiO2 System

Chonghe Li

Shanghai University, China

The composite oxides involving the V2O3, TiO2 and other oxides could be used as the oxidation catalyst or the refractory for melting the high reactive alloy, the phase diagram of the V2O3-TiO2 pseudo-binary system is the fundamental to these practical applications, however, no diagram fully assessed of this system is published. Therefore, a set of critically evaluated thermodynamic parameters of the V2O3-TiO2 pseudo-binary system is urgent needed. In order to obtain an assessed V2O3-TiO2 diagram which corresponds with the experimental data well, the existing phase diagram and thermodynamic data of V2O3-TiO2 system are assessed, and the phase diagram are calculated and optimized by using the CALPHAD technology, and some compounds with argument are discussed. In this calculation, the liquid phase, V2O3, rutile TiO2, V2TiO5, V2Ti2O7 and V2Ti3O9 are treated with the substitutional solution model. A self consistent set of the optimized thermodynamic parameters has been derived, which is in better agreement with most of the experiments. Compared with experimental data and the results in this work as well as the results reported previously, it is demonstrated that the present thermodynamic assessment is in better agreement with most of the experiments.

Key words: phase diagram; V2O3-TiO2; thermodynamics; substitutional solution model.

44


[O26]Experimental investigations of phases, phase equilibria, and melting

behaviour in the systems Fe-Al-Nb and Co-Al-Nb and their terminal binary systems

F. Stein1, M. Palm1, S. Voß1, C. He2, O. Dovbenko1,3 and O. Prymak1,4

1 Max-Planck-Institut für Eisenforschung GmbH, Düsseldorf, Germany 2 Guangxi University, Nanning, PR China

3 now at MSI Materials Science International Services GmbH, Stuttgart, Germany 4 now at University Duisburg-Essen, Essen, Germany

Experimental isothermal sections and partial liquidus surfaces of the ternary systems Fe-Al-Nb and Co-Al-Nb and new results on their binary boundary systems Fe-Al, Co-Al, Fe-Nb, and Co-Nb are presented. Microstructures, phase compositions, crystal structures, and phase transition temperatures were studied by applying differential thermal analysis, electron probe microanalysis, X-ray and high-temperature neutron diffraction as well as various metallographic methods. The ternary sections of both systems are dominated by extended phase fields of a C14-type Laves phase which in case of the Co-containing system coexists with a C15 and a C36 Laves phase. Other remarkable features are extended phase fields of the μ phase in both ternary systems and the occurrence of the very slowly forming L21-type Heusler phase Co2AlNb. Two particularly interesting results from the binary systems concern the B2 CoAl phase, which we found to have a significantly higher melting temperature than previously reported in the literature, and the ε high-temperature phase of the Fe-Al system, the crystal structure of which was unknown until recently although the existence of this phase is known since more than 100 years. Applying in-situ neutron diffraction it was shown that the ε phase has the formula Fe5Al8 and its structure is of the body-centred cubic γ1 brass type.

Keywords: Fe-Al-Nb phase diagram; Co-Al-Nb phase diagram; Fe-Nb phase diagram; B2 CoAl; ε-Fe-Al; isothermal sections; liquidus surface; Laves phases;

45


[O27]Phase Field Simulation on beta/alpha transformation in TiAlV

system coupled with CALPHAD assessment

Hang Wang, Nils Warnken, Roger C. Reed

University of Birmingham

Ti alloys are used widely for aerospace applications. However, in practice, there are some aspects of the physical metallurgy of these materials -- and particularly the beta-alloys which display the body-centered cubic (bcc) structure -- which are not well understood. Our aim here is to assess the available thermodynamic information relevant to Ti-Al-V system, and thus to design a thermodynamic database which could then be used to identify alloy compositions which are prone to the ordering reaction. This then might be used for the purposes of alloy design; since the ordering reaction is known to affect properties, one might then avoid compositions where this effect might occur. Based upon the thermodynamic driving forces calculated by the new thermodynamic database, interdiffusion in the disordered A2 phase of the ternary Ti-Al-V system is assessed and optimised. A set of parameters describing the atomic mobilities of the disordered beta phase are given, which is used in the quantitative models of alpha precipitation from beta matrix.

Key words: Phase field simulation; Ti-Al-V; CALPHAD.

[1] I. Steinbach, Modelling and Simulation in Materials Science and Engineering, 17(2009): 1. [2] F. Zhang, et al., Journal of Materials Engineering and Performance, 14(2005): 717. [3] N. Dupin and I. Ansara, Z. Metallkd, 90(1999): 76. [4] Q. Chen, et. al., Scripta Materialia, 50(2004): 471.

46


[O28]Computation Materials Design

Larry Kaufman

CALPHAD Inc., 140 Clark Road,Brookline MA 02445-5848 Inc, [email protected]

The development of High Performance Corrosion Resistant Materials(HPCRM) alloys that are damage tolerant and applicable as a coating to a wide variety of substrates under a wide range of conditions is a remarkable achievement that has been accomplished is just over two years by the dedicated efforts of experienced scientists and engineers [1] who made judicious choices in charting the direction of their work. The reduction to practice based on amorphous metal alloys has left some gaps in knowledge which has been filled by using Computational Thermodynamics based on CALPHAD Methods employed to define the unstable Fe3B phase as the nucleation site and the glass transition and T(lim), the transformation limiting temperature, as illustrated below. The iron based amorphous glasses of interest contain iron, boron, carbon, chromium, manganese, silicon, yttrium and tungsten and are subjected to a wide variety of heating and cooling rates that cover SIXTEEN ORDERS OF MAGNITUDE in the time variable that can be used to describe the synthesis, fabrication and application of these materials as bulk components or corrosion resistant coatings of useful structures.

[1] L.Kaufman, “Computational Materials Design” Journal of Phase Equilibria and Diffusion, 30, Nº 5 (2009) 418-28.

47


[O29]Thermodynamics of the Fe-Co-Mo system and modeling of early precipitation

in Fe-25 at.% Co-9 at.% Mo alloy

E. Povoden-Karadeniz1, E. Eidenberger2, P. Lang1,3, H. Leitner4,5, E. Kozeschnik1,3

1 Christian Doppler Laboratory for Early Stages of Precipitation, Vienna University of Technology, Favoritenstraße 9-11, 1040 Vienna, Austria

2 Department of Physical Metallurgy and Materials Testing, University of Leoben, Franz-Josef-Straße 18, 8700 Leoben, Austria, now: Plansee SE, A-6600 Reutte /Tirol, Austria

3 Institute of Materials Science and Technology, Vienna University of Technology, Favoritenstraße 9-11, 1040 Vienna, Austria

4 Christian Doppler Laboratory for Early Stages of Precipitation, University of Leoben, Franz-Josef-Straße 18, 8700 Leoben, Austria

5 Department of Physical Metallurgy and Materials Testing, University of Leoben, Franz-Josef-Straße 18, 8700 Leoben, Austria

Solution-treated and quenched Fe-25 at.% Co-9 at.% Mo alloys show a remarkable increase in hardness during ageing at elevated temperatures [1]. The tremendous role of semicoherent µ-phase, (Co,Fe)7Mo6 for precipitation hardening has been demonstrated in several experimental studies. Systematic investigations of the microstructure and composition of these precipitates suggest a close relation of µ-phase formation to initial decomposition processes [2]. However, up to now the mechanisms, which govern these early decomposition stages in the Fe-Co-Mo system are not well understood, and explained controversially in the literature. Chain-like regions along elastically soft <100> Matrix-directions have been interpreted either as spinodal decomposition [3], or as metastable coherent, nanoscale bcc-structured nuclei with compositions that differed significantly from the composition of macroscopic precipitates predicted by the phase diagram [4]. We apply classical nucleation theory in combination with a CALPHAD assessment of thermodynamic model parameters of the Fe-Co-Mo system, in order to verify the existence of potential precursor phases of the µ-phase in Fe-25 at.% Co-9 at.% Mo alloy. The theoretical nucleation and growth regime is distinguished from the composition range of spinodal decomposition in the Fe-Co-Mo system by calculating the coherent spinodal, with the Gibbs energies of the phases in the Fe-Co-Mo system being assessed over a wide range of temperatures. For compositions outside the spinodal, the most probable nucleus composition of nano-scaled particles can then be predicted by minimization of the critical energy of the nucleation event. Recently, this strategy has been successfully applied to the simulation of bcc-Cu precipitation in Fe-Cu [5]. Since the molar Gibbs energy is included in the minimum energy equation for the nucleation event, the thermodynamic assessment of the Fe-Co-Mo system is an essential part for a correct prediction of the nucleus composition. The determined nucleus composition of potential pre-µ precipitates in Fe-25 at.% Co-9 at.% Mo alloy is used as input parameter for the thermo-kinetic simulation of the precipitation sequence during continuous heating of solution-treated and quenched Fe-25 at.% Co-9 at.% Mo alloy. We predict nucleation and growth of bcc-type particles before the precipitation of µ-phase. The calculated composition of the pre-µ phase is in good agreement with 3D atom probe measurements.

[1] Köster W, Tonn W. Arch Eisenhuttenwes 1932;12:51. In German. [2] Eidenberger E, Schober M, Schmölzer T, Stergar E, Leitner H, Staron P, Clemens H. Phys Status Solidi A 2010;207:2238. [3] Kozakai T, Aihara H, Doi M. Trans ISIJ 1985;25:159. [4] Isheim D, Hellman OC, Seidman DN, Danoix F, Blavette D. Scripta Mater 2000;42:645. [5] Kozeschnik E. Scripta Mater 59;2008:1018.

48


[O30]Experimental investigation and thermodynamic optimization

of the Al-Mg-Nd system

Mehdi Hosseinifar

McMaster University

An addition of rare-earth (RE) metals to Mg-Al cast products results in an improved creep resistance which makes these alloys (known as AE family) suitable for automotive powertrain applications [1]. To make this material economically competitive, instead of adding rather costly individual RE elements, a less expensive mixture of them (mischmetal) is utilized. In order to realistically model the mischmetal addition, the corresponding thermodynamic database must at least include major constituents of mischmetal, namely, cerium, lanthanum and neodymium. The Al-Mg-Ce and Al-Mg-La systems are already optimized [2, 3]. To make this database complete Al-Mg-Nd system needs to be assessed as well. An obstacle hindering the assessment of the Mg-Al-Nd system is that even though limited experimental information is available in the literature [4, 5], the reliability of these data is questionable. For instance, it is proved beyond doubt that the reported liquidus temperatures are burdened with a systematic error [2, 3]. In the present investigation, the 400°C isotherm of the Al-Mg-Nd system was re-examined using diffusion couple technique. The homogeneity ranges of ternary phases in this system were determined utilizing EPMA and SEM-EDS analysis of three diffusion couples. Similar couples were also prepared at 500°C. The Determination of the solubility limits of ternary phases at two temperatures was instrumental in fixing the temperature dependent variables during optimization process. Thermal analysis experiments were conducted on two Al-rich ternary alloys. Substantially higher liquidus temperatures were recorded in the present work compared to previously reported data [5]. These high temperatures correspond to the primary solidification region of the Al11Nd3 phase. The Al-Mg-Nd system is optimized based on the experimental findings of the present study.

Key words: Mg alloys, Diffusion couple technique, Thermal analysis.

[1] M.O. Pekguleryuz and A.A. Kaya, Adv. Eng. Mater. 2003, 5(12), p. 866. [2] J. Grobner, D. Kevorkov, and R. Schmid-Fetzer, Intermetallics, 2002, 10(5), p. 415. [3] M. Hosseinifar, D.V. Malakhov, J. of Alloys and Comp., 2010, 505(2), p. 459. [4] K.H.O. Odinaev et al., Izv. Vyssh. Uchebn. Zaved., Tsvetn. Metall., 1988, 4, p. 94. [5] K.H.O. Odinaev, I.N. Ganiev, and A.Z. Ikromov, Russ. Metall., 1996, 4, p. 153.

49


[O31]Thermodynamic modeling of metastable phases in Al-Cu-Fe-Mg-Mn-Si

and applications to precipitation kinetics simulations

E. Povoden-Karadeniz1, P. Warczok2, P. Lang1,2, A. Falahati2, M.R. Ahmadi2, E. Kozeschnik1,2

1 Christian Doppler Laboratory “Early Stages of Precipitation”, Institute of Materials Science and Technology, Vienna University of Technology, Vienna, Austria

2 Institute of Materials Science and Technology, Vienna University of Technology, Vienna, Austria

Due to their good hardenability response by nano-scale metastable precipitates, Al-alloys of the Al-Cu-Fe-Mg-Mn-Si system, such as AA2024 (Al-Cu), AA6016 (Al-Mg-Si), AA6082 (Al-Mg-Si-Fe-Mn), are widely used as high-strength materials in many industrial applications. Whereas the stable phases of the Al-Cu-Fe-Mg-Mn-Si system, such as the AlFeSi-phases [1] and the Q-phase [2] have been assessed recently, a systematic CALPHAD assessment of metastable phases is not yet available. In this paper, we present thermodynamic models of metastable Mg-Si co-clusters, GP-zones, β´´-, β´-, Β´-, Υ-, Θ´´-, and Θ´-phases, which are successfully tested in thermo-kinetic precipitation simulations. Particular focus is put on the model development for disordered co-clusters and coherency strain-induced ordered particles (GP-zones) at the very early stages of precipitation (low temperatures from room temperature up to about 180°C). Specific properties of these early structures, such as their affinity to vacancies that form during quenching after solution treatment, obviously influence the precipitation of hardening phases like β´´ at higher temperatures. MgSi co-clusters and GP-zones are almost fully coherent with the fcc Al-Matrix. Hence, in a first approximation these structures are associated with the model description used for the fcc Al-Matrix: Mg-Si co-clusters are simply described as highly metastable Mg-Si solid solution (Mg,Si)(Va), and GP-zones are treated as an fcc-based ordered phase by using a split-model with 4 substitutional sublattices. For Al-Mg-Si GP-zones, the preferred sublattice occupancy then reads (Al)(Al)(Mg)(Si)(Va), analogous to the L10 structure in the case of chemical ordering. The crystallographic Mg-Si layering proposed by Matsuda et al. [3] can be reproduce. The thermodynamic model parameters of Mg-Si co-clusters are based on new energy data determined by first-principles and optimized with experimental differential scanning analysis data. Subsequent thermo-kinetic test-simulations aim at giving best reproduction of experimental particle sizes and number densities determined after various heat treatments [4].

[1] J. Lacaze, L. Eleno, B. Sundman, Metal Mater Trans A 2010;41:2208. [2] K. Chang, S. Liu, D. Zhao, Y. Du, L. Zhou, L. Chen, Thermochim Acta 2011;512:258. [3] K. Matsuda, H. Gamada, K. Fujii, Y, Uetani, T. Sato, A. Kamio, S. Ikeno, Metall Mater Trans A 1998;29:1161. [4] A. Falahati, E. Povoden-Karadeniz, P. Lang, P. Warcok, E. Kozeschnik, Int J Mater Res 2010;101:1089.

50


[O32]Assessment of the atomic mobilities for Fcc_A1 and Bcc_A2 Cu-Fe-Zn alloys

Peng Zhou1, Senlin Cui1, Dandan Liu1, Lijun Zhang1, Yong Du1,*, Wanqi Jie2

1 State Key Laboratory of Powder Metallurgy, Central South University Changsha, Hunan 410083, P.R. China

2 State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an, Shanxi 710072, P.R. China


Based on critically reviewed experimental diffusivities available in the literature, the assessment of atomic mobilities for fcc Fe-Zn, bcc Cu-Fe, Fe-Zn, Cu-Zn and Cu-Fe-Zn alloys was performed using the DICTRA software. Comprehensive comparisons show good agreements between the presently calculated diffusion coefficients and the experimental data. The reliability of the atomic mobilities obtained was further verified by comparing various model-predicted diffusion phenomena with the experimental information, such as concentration profiles, interdiffusion flux, and diffusion paths in a series of binary and ternary diffusion couples.

Figure 1 Calculated inter-diffusion coefficients of bcc Fe-Zn (a) and bcc Cu-Zn (b) alloys in comparison with the experimental data. A constant M is added to separate the data.

Acknowledgement: The financial support from National Basic Research Program of China (Grant No. 2011CB610401) is greatly acknowledged.

51


[O33]New Co-base Superalloys - Phase Equilibria and Applications

K. Ishida, T. Omori

Department of Materials Science, Graduate School of Engineering, Tohoku University

Phase stability of intermetallic compounds in Co-base alloys are reviewed compared with those in Ni-base alloys focusing on the GCP (geometrically closed-packed) phase. Although only Co3Ti is known to be a stable g’(L12) compound, there are some metastable g’ phases in the Co-X binary system such as Co3Al, Co3W, Co3Ta, etc. Recently, we discovered Co3(Al,W) ternary compound with L12 structure [1,2], which shows the positive temperature dependence on flow stress [3]. Therefore, the Co-Al-W base alloys have potential for new-type of superalloys. In this paper, the phase equilibria and some properties of Co-Al-W base alloys will be shown. The applications of this new Co-base superalloys will also be presented.

Key words: Co-base Superalloys.

[1] J. Sato, T. Omori, K. Oikawa, I. Ohnuma, R. Kainuma and K. Ishida, Science, 312 (2006) 90. [2] K. Ishida, Mater. Res. Soc. Symp. Proc., 1128 (2009) 357. [3] A. Suzuki and T. M. Pollock, Acta Mater., 56 (2008) 1288.

52


[O34]The challenge of covering thermodynamic properties not only at high temperature but also at low temperature: a progress report

M. Palumbo1, S. G. Fries1, T. Hickel2, A. Dal Corso3, M. H. G. Jacobs4, U. R. Kattner5, B. Sundman6

1 ICAMS, STKS, Ruhr University Bochum, Bochum, Germany 2 MPIE, Dep. of Computational Materials Design, Max Plank Institute, Dusseldorf, Germany

3 SISSA, Trieste, Italy 4 Institute of Technology, Clausthal Technical University, Germany

5 National Institute of Standards and Technology, Gaithersburg, MD, USA 6 INSTN CEA Saclay France

As it was pointed out recently [1], a revision of the lattice stabilities presently used in the CALPHAD community [2] is necessary to achieve a description of thermodynamic properties not only in the temperature regime above room temperature, but also in the temperature regime from room temperature down to zero Kelvin. That requires consideration of physically realistic models in Calphad methodology [3]. Our efforts in this direction are underway as part of the Sapiens project, presented in last CALPHAD XXXIX meeting held in Korea. In the present paper we report progress on this subject. To test our formalism we have selected the pure elements Cr and Ni as they are part of the selected elements of the Sapiens project. We started our analysis by collecting experimental data from the literature and results calculated by first principles methods. The reliability of these data was critically evaluated using several test criteria, such as experimental conditions, uncertainties in these data, and measuring methods. Additional, first principles calculations were carried out to determine lattice parameters, energies, bulk moduli and the vibrational contribution to the free energy in the harmonic and quasi-harmonic approach. One of the results, which we will discuss, is the partitioning of physical effects in the heat capacity. We have tested a combined approach using first principles and fitting methods. We show results of this approach by comparing our calculations with experimental data. Both the Debye and Einstein model plus additional contributions for electronic excitations, quasi and anharmonic vibrations and effects of lattice vacancies were tested by adapting optimization programs from Lukas [4]. We show a numerical scheme to calculate the Debye integral, which we implemented in this program.

Acknowledgement: ThyssenKrupp AG, Salzgitter Mannesmann Forschung GmbH, Robert Bosch GmbH, Bayer Materials Science AG, Bayer Technology Services GmbH, Benteler Stahl/Rohr AG, the state of North Rhine-Westphalia and the European Commission in the framework of the European Regional Development Fund (ERDF).

[1] B.J. Lee, A summary of the CALPHAD XXXIX conference, CALPHAD (2011), doi:10:1016/j.calphad.2010.11.005. [2] A. T. Dinsdale, CALPHAD, 15, 4 (1991) p. 317. [3] M. H. G. Jacobs, R. Schmid-Fetzer, Phys. Chem. Minerals 37, 10 (2010) p.721. [3] H.L. Lukas, Reference Manual (1995) <http://www.met.kth.se/~bosse/BOOK/lukamanu.zip>

53


[O35]Non-statistical thermodynamic optimization: an irrelevant

topic or a useful approach?

Dmitri V. Malakhov

Department of Materials Science and Engineering, McMaster University, Hamilton, Ontario, Canada

Since the CALPHAD technique is related to the least-squares method, the statistical nature of input data is implicitly assumed; it is supposed that an experimentally measured property can always be characterized by its accuracy. Even if no attention is paid to the statistical aspects of an experimental study in a publication, it is believed that the accuracy is calculable. Since such a belief is not helpful to assign statistical weights to experimental points, one asks questions like “What was the purity of substances used? Was a thermocouple calibrated? Was the equilibrium achieved?” instead of guessing, for instance, how many times a measurement was repeated. By finding reasonable answers, one guesstimates the accuracies of corresponding measurements and provides BINGSS/TERGSS, PARROT,… with the weights, but they are no longer traditional statistical weights! In contemporary publications, raw experimental data are replaced with figures visualizing them; error bars are not always shown, and even if they are, it is seldom clearly explained what they represent. Consequently, the methodological foundation of the least-squares technique becomes shaky. It is not intended to commence a hopeless struggle against a reproachable way in which experimental knowledge is disseminated today. It is contemplated to augment the CALPHAD method by a new assessment technique based on the ideas of a non-statistical treatment of experimental information formulated by Kantorovich[1] and successfully employed for solving economic problems. Methodologically, this technique better corresponds to a statistical fuzziness of experimental data used in the CALPHAD technique as input.

0 1 2 3 4 5 6 7 8 9 10

1

2

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4

5

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11 Experiment A B C

y (m

easu

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0.90 0.92 0.94 0.96 0.98 1.00 1.02 1.04 1.060.650.700.750.800.850.900.951.001.051.101.151.201.251.30

ΘB

ΘC

ΘAExperiment B

Experiment C

Experiment A

C 0 (in

terc

ept)

C1 (slope)

54


The key idea is that a measurement can be characterized by its ultimate non-statistical error. By introducing the “interval calculus”, one ceases dealing with such statistical entities as number of degrees of freedom, Student’s distribution, “three sigma” rule, and so on, but instead creates a non-statistical corridor of errors associated with experimental data and demands that any function describing them must reside within it. The left figure exemplifies a case when a property was measured in three independent examinations, A, B and C. It is worth accentuating that all error bars are the non-statistical intervals of “absolute trust” assigned to each measurement. At first glance, the results of all three experiments are in a good agreement, but an inspection of the domains of permissible slopes and intercepts shown in the right figure reveals that the outcome of the experiment B does not conform to the observations made in the experiments A and C whose domains AΘ and CΘ overlap. The example presented above is deliberately made very simple to clarify some distinctive features of the non-statistical optimization. In the presentation, more sophisticated CALPHAD-related cases are considered.

[1] L.V. Kantorovich “On new approaches to computational methods of data treatment” Siberian Mathematical Journal 1962, Vol.3, No.5, P.701-709.

55


[O36]Experimental and thermodynamic study of ternary Ni-30Cr-xC and

Co-30Cr-yC carbon-rich alloys with x and y varying from 2.5 to 5.0 wt.%

Patrice Berthod1, Lionel Aranda1, Ophélie Hestin2, Elise Souaillat2, Moussa Ba2, Ahmed Dia2

1Institut Jean Lamour, University Henri Poincaré, Faculty of Sciences and Technologies 2University Henri Poincaré, Faculty of Sciences and Technologies

Among the alloys used as coatings deposited by thermal spraying for achieving wear-resistance properties, there are Co-based alloys containing high quantities of tungsten carbides. Other alloys, containing chromium carbides and simply elaborated by foundry, may be also of interest. This study consists in an exploration of the microstructures and of the melting temperature ranges of alloys belonging to the ternary families Ni or Co (bal.) - 30Cr-xC (in wt.%), with x increasing from 2.5 to 5%, with comparison with thermodynamic calculations results. Six alloys per family were synthesized by casting. In the as-cast condition they were metallographically characterized using Scanning Electron Microscopy, with measurement of the surface fractions of the present phases (carbides, and eventually graphite). The melting-start and melting-end temperatures were also measured by DTA / DSC. Exposures to 1000, 1100 and 1200°C for 50 hours, followed by air cooling were performed for all alloys and the same microstructure characterization as for the as-cast alloys was carried out. Natures and fractions of the different phases, as well as the solidus and liquidus temperatures, were compared to results issued from Thermo-Calc calculations. All the studied nickel alloys are hyper-eutectic with presence of coarse pro-eutectic carbides in addition to the {Ni matrix + chromium carbides}-eutectic compound. Concerning the cobalt alloys, for carbon contents lower than 3wt.% their microstructures are hypo-eutectic with presence of dendrites of Co matrix delimiting the {Co matrix + chromium carbides}- eutectic spaces, while for higher carbon contents coarse pro-eutectic carbides appear while dendrites are not present anymore. Lamellar graphite also appears for the carbon contents higher than 3,5wt%C in the nickel alloys while it appears only for 5wt.%C in the cobalt alloys. In the two systems Cr7C3 carbides are present in all alloys but Cr3C2 carbides also exist in the carbon-richest alloys.

Key words: Nickel Alloys; Cobalt Alloys; Very High Carbon; Chromium Carbides; Graphite; Phase Fractions; Melting Range; Thermodynamic Calculations.

[1] P. Berthod, E. Souaillat, O. Hestin, As-cast microstructures of {M-30Cr-0 to 5%C} ternary alloys. Part 1: Nickel-Base alloys, Materials Science: An Indian Journal 2010, 6(4), 260- 266. [2] P. Berthod, O. Hestin, E. Souaillat, As-cast microstructures of {M-30Cr-0 to 5%C} ternary alloys. Part 2: Cobalt-Base alloys, Materials Science: An Indian Journal 2010, 7(1).

56


[O37]Thermodynamic properties and phase equilibria in gold-antimony-tin system determined from E.M.F., Calorimetric, and DTA/DSC methods

Dominika Jendrzejczyk-Handzlik, Wojciech Gierlotka, Krzysztof Fitzner

AGH University of Science and Technology

Using calorimetric, E.M.F. and DTA/DSC methods thermodynamic properties and phase equilibria of the Au-Sb-Sn system were investigated. Consequently, drop calorimetric measurements were carried out along the following cross-sections: -X(Au)/X(Sb) = 2:1 and 1:2 at single temperature at 1073 K - X(Au)/X(Sb) = 1:1 at two temperatures 1073 K and 923 K and integral enthalpies of mixing of liquid ternary alloys were determined at those temperatures. Next, E.M.F. measurements were done using solid oxide galvanic cells with zirconia electrolyte. The E.M.F.’s of the cells Au(1-x-y) SbxSny, SnO2//ZrO2 + Y2O3// Ni, NiO ( I ) were measured in the temperature range from 973 to 1273 K for two cross-sections X(Au)/X(Sb) = 2:1 and 1:2, and activities of tin were determined for the alloys in this temperature range. Finally, DTA/DSC measurements were done along two cross-sections - X(Au)/X(Sb) = 1:1 where X(Sn) was changed from 0.8 to 0.1 - X(Au)/X(Sn) = 1:1 where X(Sb) was changed from 0.8 to 0.1 and liquidus temperature and invariant reactions were identified. Additionally, an isothermal section of the ternary system was investigated at 473 K. All the data taken together with the information about binary systems contributed to the database used to optimize the whole ternary system.

Key words: E.M.F. method, calorimetric measurements, DTA/DSC method, isothermal phase equlibria, Au-Sb-Sn system, optimization.

57


[O38]Experimental study and thermodynamic modelling of phase relations in the

ZrO2-Sm2O3-Y2O3 and Sm2O3-Y2O3-Al2O3 systems

Olga Fabrichnaya1, Hans J Seifert2

1Technical University of Freiberg 2Karlsruhe Institute of Technology

Phase relations in the ZrO2-Sm2O3-Y2O3-Al2O3 system are important to estimate stability of new materials for thermal barrier coating applications. Thermodynamic databases of the ZrO2-Sm2O3-Y2O3 and Sm2O3-Y2O3-Al2O3 systems were derived based on binary extrapolations into ternary systems and used for selection of compositions for experimental studies. Samples obtained by co-precipitation technique were heat treated at 1250, 1400 and 1600°C. Phase assemblages formed during heat treatment were identified by XRD. Microstructures were investigated by scanning electron microscopy (SEM/EDX). Selected samples were investigated by differential thermal analysis (DTA). The obtained experimental results were used for more advanced modelling of pyrochlore phase taking into account solubility of Y2O3 in pyrochlore structure, Sm2Zr2O7. Ternary parameters were introduced into fluorite and C phases in the ZrO2-Sm2O3-Y2O3 system to reproduce experimental data. Isothermal sections of the ZrO2-Sm2O3-Y2O3 system at 1250, 1400 and 1600°C were calculated using the assessed parameters. Phases with perovskite (YAP), monoclinic (YAM) and garnet (YAG) structures in the Sm2O3-Y2O3-Al2O3 system were modelled by compound energy formalism with mutual substitution of Sm and Y in the sublattices. Calculated isothermal sections of the Sm2O3-Y2O3-Al2O3 system based on ideal mixing in YAP, YAM and YAG phases were in reasonable agreement with experimental results. Liquidus surface was predicted.

Key words: ZrO2, TBC, experimental phase equilibria, compound energy formalism.

58


[O39]The role of CALPHAD in the Science of Materials

Suzana G. Fries

ICAMS, STKS, Ruhr University Bochum, Bochum, Germany

CALPHAD was born as a method to calculate phase diagrams from modeled Gibbs energies. These models developed so soaked in experimental facts that not only phase diagrams but other quantities, like Cp curves, calculated using CALPHAD, are sometimes mistaken as they would be the genuine experiments. These calculations became so associate to CALPHAD that sometimes the method is mistaken as a computer code. An outsider looking briefly to the word can erroneous infer that CALPHAD is a code that calculates experimental facts. This misunderstanding can lead to erroneous and dangerous conclusions: no experiments are need anymore, no new models are need, all is already in CALPHAD. However, independently of the way the word CALPHAD is understood, there is an irrefutable evidence: CALPHAD is part of the needs in Materials development. One would like to have a method that would predict materials behavior like the idealized CALPHAD. Density functional theory can help in that point. However, like experimental values, the observable quantities predicted by the theory are discrete and models are still necessary to connect them. The generalized CALPHAD concept is a dynamical network of consistent information that permeates scales and adapts itself as a whole by the demands of the application in agreement to new theoretical achievements. This generalized CALPHAD should be constructed (SAPIENS project is a part of it, see Ursula Kattner and Mauro Palumbo’s lectures) and taught in materials science courses to create a connected way of thinking, independently of discipline, scale or technique. In this lecture some examples will illustrate that even if CALPHAD is just a part of alloys design it is a decisive one.

Acknowledgement: ThyssenKrupp AG, Salzgitter Mannesmann Forschung GmbH, Robert Bosch GmbH, Bayer Materials Science AG, Bayer Technology Services GmbH, Benteler Stahl/Rohr AG, the state of North Rhine-Westphalia and the European Commission in the framework of the European Regional Development Fund (ERDF).

59


[O40]Synthesis of Size and Composition Controlled Sn–xCu Nanoparticles:

Effect on the Phase Diagram and Application to Highly Conductive Ink

Yun Hwan Jo, Inyu Jung and Hyuck Mo Lee

Department of Materials Science and Engineering, KAIST, Gwahangno 335, Yuseong-gu, Daejeon, Korea 305-701

A various size of Sn-Cu nanoparticles were synthesized using a modified polyol process. Monodispersive Sn-0.7Cu (bulk eutectic) nanoparticles with diameters of 21 nm, 18 nm and 14 nm were synthesized. The peak melting temperatures of the 21 nm, 18 nm and 14 nm Sn-0.7Cu nanoparticles were 212.9°C, 207.9°C and 205.2°C, respectively, as compared with that of the bulk alloy, 230.6°C. To decrease the melting temperature further, we synthesized 14 nm Sn-xCu (x = 0, 0.7, 2.1, 4.1, 5.3 and 6.6) nanoparticles and the resultant melting temperature decreased to 200.3°C for the Sn-5.3Cu, which is 4.9°C lower than that of Sn-0.7Cu nanoparticles. The increase in the solubility limit of Cu in Sn was observed in nano-sized particles, and the composition of Sn–5.3Cu is the eutectic point in the 14 nm nanoscale phase diagram. Finally, to fabricate a low-cost, highly conductive ink for inkjet printing, we synthesized a gram scale of uniformly sized Sn nanoparticles. A 20 wt% of Sn nanoparticles was dispersed in the 50% ethylene glycol : 50% isopropyl alcohol mixed solvents. To improve the electrical property, we applied the surface treatments of hydrogen reduction and plasma ashing. The two treatments had the effect of diminishing the sheet resistance. In addition, conductive patterns (1 cm × 1 cm) were successfully drawn on the Si wafer using an inkjet printing instrument with conductive Sn ink although the maximum resistivity for an hour of sintering at 250°C was six times higher than the bulk Sn resistivity.

60


[O41]Thermodynamic Database Development of the Nd-Fe-B-Mg System for the Nd-

Fe-B Magnet Scrap Recycling Process

In-Ho Jung1, Marie-Aline Van Ende1, Hanshin Choi2, Taek-Soo Kim2

1McGill University 2Korea Institute of Technology

More than 90% of RE metals are currently produced from China. However, due to the increasing usage of RE in high-valuable electronic devices and important components for electronic, communication, automotive, etc., shortage of supply is expected in the near future. Moreover, the Chinese government limits the export of RE metals and may use it as a political weapon. In particular, Nd is one of the most critical RE elements that could face a supply constraint soon. The usage of Nd shall be increased drastically due to the application to the electrical motors in current and future hybrid and electric automotives. In addition, Nd is a quite promising alloying element for Mg alloys for high temperature and sheet applications. Thus, recycling of Nd from Fe-Nd-B magnet scraps is inevitable to keep the balance between supply and demand. Since the recycling process of the magnet materials has not been well established yet, fundamental research on the thermodynamic behaviour of Fe-Nd-B magnet materials and the chemical reactions between the magnet and solvent medium (Mg) are critical to understand and improve the Nd recycling process. In this presentation, the recent preliminary thermodynamic modeling (CALPHAD) results of the quaternary Fe-Nd-B-Mg system will be presented. Then, the applications of the database for the pyrometallurgical recycling of the Nd-Fe-B magnet using liquid Mg solvent will be presented.

Key words: Mg-Nd-Fe-B system, Nd permanent magnet, recycling.

61


[O42]Nonequilibrium phase transformation calculation with Energetics

Shihuai Zhou1,*, R.E. Napolitano2

1 Materials & Engineering Physics Program, Ames Laboratory, USDOE 2 Materials & Engineering Physics Program, Ames Laboratory, USDOE;

Department of Materials Science and Engineering, Iowa State University Ames, Iowa 50011, USA


The energetics is employed to calculate the nonequilibrium phase transformation. For the extreme condition i.e. no chemical partitioning, T-zero lines are used to describe diffusionless phase transformation. Between two-terminal cases, i.e. phase equilibrium and zero chemical partitioning, a continuum exists. To describe this continuum, we introduce a parameter, eta=((realMu)-(T-zeroMu))/((equMu)-(T-zeroMu)), named as the degree of chemical partitioning. For a given temperature, the variation of eta from 0 to 1 indicates the increasing minimum diffusional burden that accompanies the phase transition for the composition range between T-zero and Tequ. Thus, level curves with respect to eta in the composition-temperature domain represent possible nonequilibrium phase transformation. The nonequilibrium phase transformations for Al-Sm and Pd-Si systems will be presented.

Key words: nonequilibrium phase transformation, Pd-Si,Al-Sm.

62


[O43]Experimental investigation and thermodynamic calculation

of the Mn-Ni-Si System

Biao Hu1, Honghui Xu1,*, Shuhong Liu1, Yong Du1, Cuiyun He2, Chunsheng Sha1, Wenqing Zhang3, Yingbiao Peng1, Dongdong Zhao1 and Yiwei Li1

1 State Key Laboratory of Powder Metallurgy, Central South University, Changsha, Hunan, 410083, P. R. China

2 School of Materials Science and Engineering, Guangxi University, Nanning, Guangxi, 530004, P. R. China

3 State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Chinese Academy of Sciences, Shanghai, 20050, P.R. China


The Mn–Ni–Si system has been investigated via thermodynamic modeling coupled with key experiments. The isothermal section at 1000oC was determined by means of XRD and SEM/EDX. The present experimental data confirmed 7 out of 8 ternary compounds (τ1, τ3, τ4, τ5, τ6, τ7, τ11 and τ12) reported in the literature. Based on the critically reviewed experimental data available in the literature and the present experimental data, a thermodynamic modeling is performed. One single function was used to describe the Gibbs energies of the ordered/disordered transitions for Fcc_A1/L12 and Bcc_A2/Bcc_B2. A set of self-consistent thermodynamic parameters of the Mn-Ni-Si system has been obtained. Comprehensive comparisons between calculated and measured phase diagrams show that the measured isothermal sections at 800 °C and 1000 °C are satisfactorily accounted for by the thermodynamic description.

Fig 1. Calculated isothermal section at 800°C along with the experimental data.

Acknowledgements The financial support from the National Natural Science Foundation of China (Grant Nos. 50971135, 50721003 and 50831007) is greatly acknowledged

63


[O44]The Phase Diagrams Ta-V-{Si,Ge}

Atta Ullah Khan1, Pavel Broz2, Haiyang Niu3, Xingqiu Chen3, Peter Rogl1

1Institute of Physical Chemistry, University of Vienna, Währingerstrasse 42, A-1090 Wien, Austria 2 Masaryk University, Faculty of Science, Department of Chemistry,

Kotlarska 2,611 37, Brno, Czech Republic 3Shenyang National Laboratory for Materials Science, Institute of Metal Research,

Chinese Academy of Sciences, Shenyang, 110016, P. R. China

Due to low induced activity under neutron irradiation Ta-V are important constituents in CrWVTa martensitic steels developed for fusion reactors. Therefore, reliable experimental phase equilibria data as well as thermodynamic description of phase stability in the Ta-V-Si subsystem are needed for successful materials design. Although phase relations have been reported for an isothermal section of the Ta-V-Si system at 1400°C [1] contradictions arise with Laves phases Ta(V,M)2 claimed to exist [2] for M=Si and for the homologue Ge for which no phase diagram is hitherto available. Phase relations in the systems Ta-V- {Si,Ge} have been reinvestigated in this work (based on optical microscopy, X-ray microanalyses and X-ray powder analyses of arc melted and annealed alloy specimens) and are characterized by continuous solid solutions (Ta,V)Si2, (Ta,V)5Si3, extended solids solubilities (Ta,V)6Si5 and Laves phase compounds with two structure types MgZn2 and MgCu2. Based on thermodynamic assessments of binary subsystems [3-5] and ab-initio data for the ground state energies of the end members of the solid solutions a CALPHAD modeling was performed to provide a consistent set of thermodynamic data in the Ta-V-Si system.

Financial support by MEB 060915 and CZ 11/2009 of WTZ-ÖAD are gratefully acknowledged. Phase equilibria were calculated by means of Thermocalc code. X.-Q. Chen acknowledges the support from the “Hundred Talents Project” of CAS.

Keywords: Laves phases, phase analysis, CALPHAD, ab-initio calculations.

64


Abstracts: Oral Presentations, May 25 (Wednesday)

Applications - Energy

65


[O45]The Phase Diagram Basis U-M-Si for LEU fuels; M = Al, Sc to Pt

Peter Franz Rogl1, Henri Noel2

1Institute of Physical Chemistry, University of Vienna, Austria 2Laboratoire de Chimie du Solide et Materiaux, UMR-CNRS 6226,

Universite de Rennes I, France

The talk intends to present an overview in the phase relations, compound formation and compound properties in the ternary systems U - Metal M - Silicon, where M stands for aluminium and for a transition metal of groups III to VIII. The research reported herein is related to low enriched uranium (LEU) proliferation resistant reactor fuel systems. Phase relations in the systems U-M-Si were mainly established for isothermal sections in the range from 800° to 1400°C based on optical microscopy, X-ray microanalyses and X-ray powder analyses of arc melted and annealed alloy specimens. X-ray single crystal data analyses and neutron powder refinement assisted in elucidating the crystal as well as magnetic structures of ternary compounds. Most of the ternary compounds for M=Ti to Re are weakly magnetic with rather low saturation moments - The magnetic properties will be discussed as well as systematic trends in the formation and crystal chemistry of the compounds in the ternary systems U-M-Si. Stability of competing phases has been evaluated for selected cases by means of ab-initio calculations.

Key words: ternary systems U - Metal M - Silicon, phase relations, compound formation, compound properties.

66


[O46]Experimental study on the microstructure factors controlling the

corrosion behavior of Zr alloys

Jeong-Yong Park, Hyun-Gil Kim, Byung-Kwon Choi, Sang-Yoon Park, Yang-Il Jung, Dong-Jun Park

Korea Atomic Energy Research Institute

The development of the advanced nuclear fuel claddings with improved corrosion resistance has been widely carried out in many countries operating nuclear power plants. The fact that Nb was selected as a major alloying element in Zr-based alloy is the common characteristics of the newly developed fuel claddings. Although a number of researches were carried out to evaluate the corrosion behavior of Nb-containing Zr alloys, the optimum Nb content for corrosion performance was changed according to chemical compositions and manufacturing processes. It is essentially required to investigate the microstructure factors controlling the corrosion behavior of Zr alloys for developing the advanced nuclear fuel cladding with superior corrosion resistance. In this study, the effects of alloying elements, microstructure and the processing parameters on the corrosion behavior have been intensively investigated using the various types of Nb-containing Zr alloys. The microstructure of the alloys was observed by a transmission electron microscopy. The types of precipitates in the alloys were identified by analyzing the selected area diffraction pattern and the chemical composition from the energy dispersive X-ray spectroscopy. Corrosion tests of the alloys were performed in PWR-simulating condition by using static autoclaves. The addition of Sn showed a deleterious effect of the corrosion resistance of Nb-containing Zr alloys as in Zircaloy-type alloys. The corrosion behavior of Zr-xNb alloys was significantly different depending on the Nb content and the annealing temperature during the manufacturing process, which in turn determines the precipitate characteristics. The corrosion resistance of the Nb-containing Zr alloys was apparently degraded with having beta-Zr phase and increasing size of the precipitated intermetallic compounds, which was resulted from increasing of intermediate and final annealing temperature.

Key words: Zr alloys, Microstructure, Precipitate, Corrosion.

[1] J.Y. Park, B.K. Choi, Y.H. Jeong, Y.H. Jung, Journal of Nuclear Materials, Vol. 340, 2005, pp. 237-246. [2] J.Y. Park, B.K. Choi, S.J. Yoo, Y.H. Jeong, Journal of Nuclear Materials, Vol. 359, 2006, pp. 59-68. [3] J.Y. Park, Y.H. Jeong, Y.H. Jung, Metals and Materials International, Vol. 7, 2001, pp. 447-455.

67


[O47]Simulation of Oxide Dissolution in Zr Alloys : Comparison between Numerical

EKINOX Code and DICTRA Calculations

C. Toffolon-Masclet1, C. Desgranges2, B. Mazères2, D. Monceau3

1CEA-DEN/DMN/SRMA/LA2M, 2CEA-DEN/DPC/SCCME/LECNA,

3CIRIMAT-CNRS / ENSIACET

High Temperature (HT) oxidation (T>1000°C) of Zr alloys involves phase transformations controlled by oxygen diffusion in the substrate. Indeed, once the O solubility limit in the β-Zr phase is reached, the phase transformation β-Zr→ α-Zr begins, leading to the growth of both an oxygen stabilized α-Zr (O) layer and an outer oxide (ZrO2) layer once the O solubility in α-Zr has been reached. In the case of HT oxidation of a pre-oxidized material, that is a Zr alloy with an external transient ZrO2 layer formed at lower temperatures (i.e. ~350-400°C), a dissolution of the transient oxide is observed in the first steps of the subsequent HT oxidation [1]. The kinetics of this dissolution stage has been investigated using two different numerical tools. The first one is a numerical code called EKINOX formerly developed to treat HT oxidation of Fe and Ni alloys [2]. This code has been recently adapted in order to solve out HT oxidation of Zr alloys [3]. It has also been coupled with the Zircobase thermodynamic database [4] via the TQ interface in order to obtain accurate equilibrium concentrations values in each phase. The second tool is the DICTRA software coupled with the Zircobase and the Zircomob database . Zircomob is the first mobility database dedicated to Zr alloys [5]. Oxygen diffusion profiles have been calculated inside the three phases involved in this dissolution process using both tools and compared.

Key words: Zr alloys, Diffusion, oxidation, Thermocalc, Dictra.

[1] J.-C. Brachet et al., Journal of ASTM International, Vol. 5, No. 5, Paper ID JAI101116, (2008), Available online at www.astm.org. [2] N. Bertrand et al.: Mater. Sci. Forum Vol. 595-598 (2008), p. 463. [3] C. Corvalan-Moya et al.: J. Nucl. Mater., Vol.400 (2010), p. 196c.

68


[O48]Physico-chemical properties investigation of plutonium

O. Beneš, R. J. M. Konings, D. Staicu

European Commission, Joint Research Centre, Institute for Transuranium Elements, Postbox 2340, 76125 Karlsruhe, Germany

Actinides are 5f elements that are unstable, undergoing radioactive decay. As a result of the complexity of their handling and also their availability, it is difficult to experimentally investigate their properties. Special cases are uranium and plutonium which have been studied extensively as they are fissile materials used in nuclear technology, e. g. as a fuel in nuclear reactors. One of the key properties that determine thermodynamic stability of a material is the heat capacity. In case of plutonium element, several experiments have been performed to investigate this quantity; however the data are in significant disagreement as shown in Figure 1. Moreover for the high temperature ε-phase and for the liquid phase only very few points have been measured, with very large scatter. Therefore new measurements are needed to obtain more reliable description. In this study we present new experimental data of the enthalpy increments of the α-, β-, γ-, δ-, δ’-, ε- and liquid plutonium which were measured in the Institute for Transuranium Elements (JRC-ITU) using a drop calorimeter. For the liquid phase determination special measures have been introduced. From the obtained data the heat capacity has been derived and correlated with a direct measurement using differential scanning calorimeter, performed in JRC-ITU as well. Both apparatuses are installed in an alpha tight glove box which made it is feasible to handle this radioactive element. Furthermore the enthalpies of transitions between various phases were identified and correlated with the literature. The set of new data has been implemented in the thermodynamic database of the actinide elements and used in the thermodynamic modelling of the p-T phase diagram of plutonium which will be shown in this study. In order to describe this system the unknown thermal expansion coefficients and the bulk modulus of plutonium phases had to be optimized, giving the novel data.

Fig. 1. A compilation of the high temperature heat capacity data of plutonium element taken from [1].

[1] R. J. M. Konings, O. Beneš, The thermodynamic properties of f-elements. Part I. The Lanthanide and Actinide Metals, J. Phys. Chem. Rev. Data, 39 (2010) 3

69


[O49]Thermodynamic assessment of a Molten Salt Reactor fuel

M. Beilmann, O. Benes, R. Konings

European Commission, Joint Research Centre, Institute for Transuranium Elements

The Molten Salt Reactor (MSR) is a nuclear reactor type with great potential in terms of safety and security. For this reason it is considered in the Generation IV International Forum as one of the six next-generation nuclear energy systems. In this reactor type the fissile material is dissolved in a matrix of molten fluoride salts which acts as solvent and coolant in parallel. The whole fluid salt mixture circulates between the reactor core, where it is heated up, and the heat exchangers. Today the research concentrates on concepts with a non-moderated (fast) neutron spectrum which offers new prospects. Depending on the reactor design the MSR can be operated as actinide burner as well as breeder reactor in which 233U is bred from 232Th. In this context CALPHAD is a very strong tool to support further reactor developments and the decision about the final fuel composition. With this method several thermodynamic properties of the salt are accessible. As a possible multi component fluoride salt mixture for the breeder design we assessed the LiF-NaF-CaF2-ThF4-UF4 system using the CALPHAD approach. The excess Gibbs energies of the liquid solutions have been modelled with the modified quasi chemical model and for the solid solutions we applied a polynomial formalism. To model the higher order systems the binary systems were extrapolated according the asymmetric Toop formalism. These calculations are based on the available literature data as well as on own differential scanning calorimetry (DSC) measurements on several subsystems using special tools to work with fluoride salts and with radioactive samples. From the obtained description we were able to derive some important thermodynamic properties such as melting temperature, vapour pressure or boiling points.

Key words: Phase diagram assessment, Molten Salts, differential scanning calorimetry, thermodynamics.

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[O50]The thermodynamic database of nuclear material system

X.J. Liu, C.P. Wang

Xiamen University, China

A good understanding of nuclear materials is important to develop a safe nuclear reactor with high efficiency, however, traditional methods of materials research solely based on experimental investigations are far from being suitable for probing nuclear materials properties because of the stringent experimental conditions. The investigation of phase diagrams of nuclear material systems is essential for the development of new nuclear materials. Our goal is to develop a thermodynamic database and phase diagrams for nuclear materials. In this work, the thermodynamic assessments of phase diagrams in the binary and ternary systems with rare earth elements have been carried out by using CALPHAD method on the basis of the experimental data including thermodynamic properties and phase equilibria. Gibbs free energies of the solution phases were described by subregular solution model with the Redlich-Kister equation, and those of the intermetallic compounds and gas phase were respectively described by sublattice model and ideal gas model. A consistent set of thermodynamic parameters have been derived for describing the Gibbs free energies of each solution phase and intermetallic compound. The calculated phase diagrams and thermodynamic properties are in good agreement with the experimental data. The thermodynamic database includes the commonly used elements in the nuclear materials, for example: Th, Pu, U, Al, C, Co, Cr, Cu, Fe, Mg, Mn, Mo, Nb, Ni, Pb, Sc, Si, Sn, Y, Zn and Zr.

Key words: Thermodynamic Database; Nuclear Materials; CALPHAD.

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[O51]Thermodynamic modelling of oxide fuels containing minor actinides

(U, Pu, Am, Np) O2± x

Gueneau Christine1, Gotcu Petronela2, Benes Ondrej2, Sundman Bo3, Dupin Nathalie4, Konings R.J.M.2

1CEA Saclay - DEN/DANS/DPC/SCP/LM2T 2European Commisiion - JRC - ITU

3CEA Saclay - INSTN 4Calcul Thermodynamique

Uranium dioxide UO2 and mixed oxide (U, Pu) O2 fuels have already been used in thermal and fast reactors. For the next generation of nuclear reactors, the recycling of minor actinides (Np, Am, Cm) in the fuel is considered. The goal is to destroy the minor actinides by neutron fission (transmutation). Fuels with low (few percent) and high content (up to 40%) of minor actinides are studied for the fast reactors. In fast reactors, a steep temperature gradient exists in the fuel pins. In some regions, the fuel can be exposed to temperatures above 2300 K during operation. Thus the use of such fuels requires a good knowledge of the high temperature thermodynamic properties of the U-Pu-Am-Np-O system. For that, a thermodynamic modelling of this complex system has been undertaken using the Compound Energy Formalism to describe the fluorite oxide phase (U, Pu, Am, Np) O2. A three sublattice model with ionic species is used: (U+3, U+4, U+5, Am+3, Am+4, Np+3, Np + 4) 1 (O-2, Va) 2 (O-2, Va)1 where “Va” designate vacancies. The model will be described. Calculations of key properties such as oxygen potentials and vapour pressure data will be presented and compared to available experimental data.

Key words: Thermodynamic assessment - Nuclear fuels - Oxide fuels - Minor actinides.

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[O52]Investigation in the CaO-SiO2-M2O (M= Na, K) system

Ligang Zhang, Patrick J. Masset

TU Bergakademie Freiberg, Centre for Innovation Competence Virtuhcon, Germany

The aim of VIRTUHCON is the theoretical modelling of high temperature conversion processes and metallurgy and gasification. The thermodynamic properties of molten oxides systems (slag) are essential as important feature for the modeling of such processes. Compared to experimental methods thermodynamic equilibrium modeling is able to generate results within less time at lower costs. In order to perform calculations concerning systems which have a complicated structure and strong interactions between the constituents an adequate thermodynamic model and assessed thermodynamic data are needed. The accuracy of the calculation depends on the reliability of the database and adaptability of the model.The goal of the present work is to describe the thermodynamic properties of the ternary CaO-SiO2-M2O where M is an alkali oxides. Some of the binary systems (SiO2-M2O) have been already optimized and the parameters data in the literatures have been used to extrapolate in the ternary system. The missing binary systems have been assessed and the results were used for the optimization of the ternary system. The ionic two-sublattice model was applied to represent the phase relations in the CaO-SiO2-Na2O and CaO-SiO2-K2O. The phase equilibria calculated the new optimized slag solution data show good agreement with the experimental points.

Key words: Slag system; Phase diagram, heat capacity, CALPHAD.

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[O53]Application of FactSage for the Study of Slagging In Entrained-Flow Gasifiers

Marc A. Duchesne1,2, Robin W. Hughes2, Dennis Y. Lu2, David McCalden2, Arturo Macchi1, Edward J. Anthony2

1University of Ottawa 2CanmetENERGY

FactSage is a powerful tool for the prediction of thermodynamic properties and equilibrium states. To demonstrate its relevance in the field of fossil fuel gasification, particularly slagging behaviour, three applications are discussed. The liquid and solid phases present in fly ash and on the gasifier wall dictate ash sticking propensity. Hence the first application is the calculation of ash equilibrium states and liquidus temperatures for coal and petroleum coke ash. The FactSage calculated results are compared to SEM-EDX analysis of quenched fly ash samples and wall slag samples collected from CanmetENERGY’s high pressure 1 ton/d gasifier. Secondly, since slag-refractory interactions such as dissolution and spalling are major concerns for the design and operation of gasifiers, two types of refractory test rods (SiC and 70 wt% Cr2O3-30 wt% Al2O3) were exposed to ash constituents in CanmetENERGY’s gasifier. Phases predicted via FactSage are compared to compounds detected by SEM-EDX at the slag-refractory interface. Thirdly, slag viscosity affects slag-refractory interaction and slag accumulation along the reactor walls. The latter will affect heat transfer within the reactor and could possibly lead to slag tap plugging. Slag viscosity models which make use of FactSage calculations are quantitatively compared to viscosity measurement results, and qualitatively compared to slag thickness on CanmetENERGY’s gasifer refractory. Many challenges remain with the use of thermodynamic modeling to predict gasifier slagging phenomena, such as determining vanadium equilibrium states, implementation of thermodynamic models within comprehensive reactor models, working with complex multi-component systems and adjusting predictions for non-equilibrium conditions. These are discussed in the context of each application.

Key words: FactSage, slag, silicate melt, vanadium.

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[O54]Evaluation of the thermodynamic properties of the gas phase

involved in gasification processes

Patrick Masset, Cuiping Guo

TU Bergakademie Freiberg

Gasification processes are operated at elevated temperatures (1000-1500 °C) depending of the technology used in order to produce syngas (mainly hydrogen and carbon monoxide) employed in chemical engineering plants. At high temperatures, part of the mineral matter (SiO2, Na2O, K2O.) contained in the ash/slag arising from the original coal vaporizes. In the reactor volatiles species react with oxygen, water vapour and carbon (CO, CO2.) based gaseous species. This work aims at determining the thermodynamic properties of species formed at elevated temperatures and their range of stability as a function of the process conditions (temperature, oxygen, CO/CO2 partial pressures, total pressure.) encountered in such high temperature process. This evaluation provides a new description of the gas phase properties which may react with solid phases (ash, structural materials) or liquid phases (slag) and may be used in flow sheet s of process description.

Key words: Thermodynamic properties, gas phase, gasification process.

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[O55]Evaluation of the Chemical Composition of Irradiated Mixed Carbide Fuel

Jean-Christophe Dumas, Jean-Paul Piron, Chantal Martial

Commissariat à l’Energie Atomique, DEN/DEC/SESC - CEA Cadarache - 13108 Saint-Paul Lez Durance Cedex, France

The mixed carbide (U,Pu)C is a reference material for Generation IV (Gas-cooled Fast Reactor or Sodium Fast Reactor) nuclear fuels. The creation of fission products (FP) can modify the physical and chemical properties of the fuel behaviour during irradiation. As they control the carbon activity in the fuel, it is important to assess the influence of burn-up and temperature on the speciation of FP (solid, liquid and gaseous phases). The first part of this study is dedicated to the thermodynamic modelling of the irradiated fuel introduced into the FactSage code. The second part deals with the evaluation of the chemical state of the fission products as a function of burn-up and initial composition (carbon content) for representative operating temperature values. For that purpose, we have used the isotopic composition data given in [1] and compared our results to those obtained with the Solgasmix-PV computer program code and also to experimental observations on irradiated fuels from [2]. Special attention is paid to the evolution of the carbon over metal (C/M) content with burn-up. Indeed, as the C/M ratio decreases with burn-up, the initial M2C3 phase present in the fuel might disappear as soon as C/M decreases below one and due to the narrow non-stoichiometry of the MC phase [3,4], a liquid (U,Pu) phase might appear, which is not recommended for safety criteria. Finally, comparison of our results obtained on of un-irradiated (U,Pu)C fuel (isothermal ternary sections, carbon and plutonium activities) with those calculated by the TCC Software using the CALPHAD description of the (U-Pu-C) system developed in the frame of the FuelBase Project [5] shows significant differences. Those last results lead us to conclude that a complete CALPHAD description of the whole (U-Pu-C-FP) system would be helpful if we want to improve the operating conditions of this kind of fuel.

Key words: Nuclear Fuels, Mixed Carbide, Fission Products, Chemical Composition, FactSage, Thermo-Calc, FuelBase Project.

[1] R. Agarwal, V. Venugopal, J. Nucl. Mater. 359, 122 (2006). [2] Hj. Matzke, Science of Advanced LMFBR Fuels, Elsevier Science Publishers B.V. (1986). [3] H. Kleykamp, J. Nucl. Mater. 221, 131 (1985). [4] H. Holleck, Thermodynamics of Nuclear Materials, IAEA Vie.

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Abstracts: Oral Presentations, May 26 (Thrusday)

Applications - Steel, Superalloys, Oxides

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[O56]Applications of CALPHAD in Steelmaking and Future Scope

Tooru Matsumiya

Nippon Steel Corporation

CALPHAD has been used to control the chemical compositions of nonmetallic inclusions such as for sulfide shape control in anti-hydrogen-induced-cracking steel for line pipe and softening oxide inclusions in austenitic stainless steel for wire, to design the compositions of continuous casting flux which prevents from casting sticking to the mold for titanium bearing steel, to optimize hot metal demanganization process, and so on in steelmaking field. In order to utilize CALPHAD, thermodynamic data are required. When they are not available, ab itnitio based calculations of phase equilibrium and thermodynamic property values are expected to give help. From that viewpoints, we conducted phase diagram calculation of Au-Cu system with the combination of Monte Carlo simulation and interaction energy values obtained by application of cluster expansion method to total energy calculated ab initio and estimated activity coefficients and interaction parameters of solutes in dilute silicon solution by the use of density functional theory. In addition, excess entropy of mixing was included in the estimation of activity coefficient of oxygen in silicon by applying grand canonical Monte Carlo simulation. Since high performance computers will be available in near future, such as 10 PFLOPS computer in Japan in 2012, ab initio estimation of thermodynamic properties and atomistic simulation should be utilized more than before in the combination with CALPHAD method in various ways.

Key words: sulphide shape control, nonmetallic inclusion, mold powder, Monte Carlo simulation, activity coefficient, interaction parameter.

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[O57]Application of the CALPHAD method for ferritic boiler steels

André Schneider

Boiler & Line Pipe Competence Center, Vallourec Research Düsseldorf, V & M Deutschland GmbH

An overview of past and current applications of the CALPHAD method on various questions concerning ferritic boiler steels is given. The focus is on the development of high-temperature steels, on welding and on life-time predictions. The different concepts on the improvement of properties such as creep strength, corrosion resistance and weldability are reported. In view of developing or improving steels for the application in conventional power plants various elements have been tested with respect to a controlled precipitation of chromium carbides, carbonitrides and the intermetallic Laves phase. The thermodynamic calculations were mostly used for identifying alloy compositions being necessary for the evolution of the desired microstructures and precipitations. The kinetic simulations are often focussed on diffusion-controlled transformations during heat-treatment, welding and application in the power plant. A key-issue is the life-time prediction for 100.000 hours and more including all aspects such a nucleation, growth and coarsening of precipitates.

Key words: CALPHAD.

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[1] G. Eriksson, Acta Chemica Scand, 1971, Vol. 25, p. 2651. [2] G. Eriksson, E. Rosén, Chemica Scripta, 1973, 4, 193. [3] G. Sigworth, J. Elliot, Metal Science, 1974, 8, N° 9, p. 298. [4] X. Zhang et al, Calphad, 1997, 21, N° 3, p. 301. [5] X. Zhang et al, Calphad, 1997, 21, N° 3, p. 311. [6] M. Garlick et al, Ironmaking and Steelmaking, 2002, 29, N° 2, p. 140. [7] K. Ogawa et al, Tetsu to Hagané, 1985, 71, N° 2, p. A29.

[O58]Development of a model to predict inclusions composition in steels deoxidized

with aluminum, silicon and manganese

Carlos Cicutti, Constantino Capurro

Tenaris R&D

The composition of non-metallic inclusions may affect steel castability and also have a strong impact on the properties of final product. In the present work, a model to predict the composition of inclusions in equilibrium with liquid steel was developed. Knowing the total composition of steel and temperature, the amount of dissolved elements in the melt and the composition of inclusions are calculated. Following the procedure proposed by Ericksson [1-2], an in-house code was developed which minimizes the free energy of the system keeping a mass balance of the involved species. In this particular case, the model was applied to study the inclusions formed during deoxidation of steel with Al, Si and Mn. Activities of dissolved elements in liquid steel were calculated using Wagner’s formalism [3]. Activities of oxides in Al2O3-SiO2-MnO system were estimated using the sub-regular model proposed by Zhang [4-5]. Model results were compared with measurements previously reported in the literature [6-7] and also with experimental work carried out in this study. In general, a reasonable agreement between measured and calculated values was obtained. Hence, the model was used to analyze the effect of steel composition on the type of non-metallic inclusions expected. The amount of aluminum and ferroalloys that have to be added to ensure (or to avoid) alumina as deoxidation product was determined.

Key words: Inclusions, steel, deoxidation, model, equilibrium.

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[1] http://www.micress.de. [2] http://www.thermocalc.com. [3] J. Eiken, B. Böttger, I. Steinbach, Phys. Rev. E 73 (2006), 066122.

[O59]Phase-Field Modelling of Technical Alloy Systems

Bernd Böttger

Access e.V, RWTH Aachen University

Despite of the importance of thermodynamics for material science and processing, material structures and properties or optimised parameters for industrial processes typically cannot be obtained from pure thermodynamic considerations. The reason for this is the predominant role of diffusion and interfacial kinetics for microstructure formation and thus for the materials behaviour and properties during the process. This conclusion does not curtail the needs for improved thermodynamic descriptions, but highlights the importance of a further coupling of these thermodynamic data to simulation tools like MICRESS [1] or DICTRA [2] which include diffusion and phase transformations. In this paper, details are shown how a phase-field model [3] has been coupled to CALPHAD-type thermodynamic databases. The aim is to develop and continuously improve the commercial software tool MICRESS which allows for modelling of microstructure formation in technical alloys during manifold processes like casting, heat treatment, deformation and service. Emphasis is placed on the pragmatic formulation of the phase-field model, which allows for use at different length scales, as well as on a general and effective coupling scheme to thermodynamic data by integration of the Gibbs energy minimising software Thermo-Calc [2], facilitating the use with manifold alloy systems and databases. Furthermore, specific topics related to technical alloy systems like the treatment of stoichiometric phases, composition sets, miscibility gaps etc. are discussed.

Key words: Phase-field, MICRESS, technical alloys, microstructure, simulation, diffusion, phase transformation, software.

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[1] G. Cacciamani, A. Dinsdale, M. Palumbo, and A. Pasturel, “The Fe–Ni system: Thermodynamic modelling assisted by atomistic calculations”, Intermetallics, 18 (2010) 1148-1162. [2] B. Jonsson, “Mobilities in Fe-Ni alloys - assessment of the mobilities of Fe and Ni in fcc Fe-Ni alloys”. Scandinavian Journal of Metallurgy, 23 (1994) 201-208. [3] M. L. Yunker, J. A. Van Orman, “Interdiffusion of solid iron and nickel at high pressure”, Earth and Planetary Science letters, 254 (2007) 203-213.

[O60]Diffusion in Fe-Ni PM alloys: microstructure and DICTRA simulations

T. Gómez-Acebo, F. Castro

CEIT and Tecnun (University of Navarra) Manuel Lardizabal 15. E-20018 San Sebastian, Spain

In the Fe-Ni-C alloy system the interdiffusion of Fe and Ni has been studied under several combinations of time and temperature. The interest in studying this system is contemplated within the frame of powder metallurgy, so that Fe, Ni and carbon powder mixtures have been used as raw materials for the preparation of the studied samples containing different amounts of admixed Ni. The studied compositions are Fe-0.8 wt% C-2 to 6 wt% Ni, with varying particle size of the Ni powders (< 1.0 and ≈7 µm) while the mean particle size for the Fe powders are ≈70 µm. Sintering was carried out at temperatures between 1120 and 1280 ºC with holding isothermal periods between 0.5 and 4 h. After sintering the microstructures of the experimentally obtained samples were characterised by optical and scanning electron microscopy. The experimental results were compared with diffusion simulations using the last available thermodynamic [1] and kinetic [2] descriptions of the Fe-Ni system, using DICTRA. The simulations have confirmed recent experimental observations [3], in which Fe diffusivity is higher than that of Ni. Interpretation of the different microstructures, obtained at different combinations of time and temperature, was allowed by considering effective diffusion distances including the influence of particle sizes. For high Ni particle sizes, there are sintering times and temperatures in which the chemical composition of the Ni-containing regions cannot be homogenised. This has proved very useful for the design of sintering cycles of Fe-Ni components made by powder metallurgy.

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[O61]Simulation of an Industrial Solidification Process by

Coupling CALPHAD and Phase-Field

Philippe Schaffnit, Juliane Mentz, Joachim Konrad

Salzgitter Mannesmann Forschung GmbH

The solidification of small portions of steel melts is part of almost all welding operations in steel applications. During the investigated welding operations the prepared edges of the steel material are heated up to high temperatures and pressed together. A characteristic depletion of alloying elements can be observed in the bond line formed by material in a semi-liquid state. This depletion influences the mechanical properties of the steel construction. The mechanisms leading to this element distribution have not been fully described yet. The highly dynamic nature of the process precludes experimental investigations, making computational simulation a unique mean of gaining insight in this industrial process. The microstructure evolution and subsequent element redistribution upon the heating of the material were simulated by combining thermodynamic calculations and phase field modelling with the commercial code MICRESS. Experimental data provided the element distribution and microstructure at room-temperature. The re-distribution of elements in presence of a liquid phase was calculated on the basis of CALPHAD data, and the final element distribution was determined assuming that most of the liquid phase has been squeezed out of the bonding zone. The simulated bond line reveals a zone depleted of alloying elements and small regions of re-solidified material enriched in alloying elements. The simulation results were compared to microprobe measurements of industrially solidified samples and show a good agreement regarding the element contents and distribution. As a result of these findings the knowledge based optimization of process parameters should lead to improved mechanical properties of the bonding. Simulated manganese distribution at 1500°C

Keywords: Steel, Welding, Phase-field, Industrial application.

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[O62]How applications drive thermodynamics towards

fundamental considerations

Malin Selleby

Department of Materials Science and Engineering, KTH (Royal Institute of Technology), SE-100 44 Stockholm, Sweden

Many of the core binary systems for steels were evaluated during the 1980’s. In 1991 SGTE compiled thermodynamic descriptions for pure elements, and those descriptions were used to harmonize the development of databases. Now, 20-30 years later, it is time to renew these descriptions of elements, extend them to 0 K, better describe the magnetic contribution and revisit all important binary and ternary systems. The VINN Excellence Center Hero-m at KTH is working closely together with industry to be able to improve industrial materials like high strength steels, advanced stainless steels, cemented carbides but also new materials like bulk amorphous alloys. In order to fully understand the underlying mechanisms of microstructural development we need to model e.g. the martensitic transformation, the spinodal decomposition in duplex stainless steels and the formation of bainite. In our attempts to do so, it has proven necessary to revisit and reevaluate some of the current descriptions used in many of the commercial databases. It will be demonstrated how applications to real industrial processes have urged us to reevaluate both thermodynamic models and descriptions.

This work was performed within the VINN Excellence Center Hero-m, financed by VINNOVA, the Swedish Government Agency of Innovation Systems, Swedish Industry and KTH (Royal Institute of Technology).

Key words: Applications, thermodynamics, industrial materials.

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[O63]Applications of CALPHAD in Cemented carbide development

Henrik Strandlund1, Susanne Norgren2

1Sandvik Tooling, R&D Materials and Processes, SE-126 80 Stockholm, Sweden 2Sandvik Mining and Construction R&D, CCHM, SE-126 80 Stockholm, Sweden

Cemented carbides used for metal cutting tools and rock drilling are most often WC-Co based alloys. Within the cemented carbide industry there is a great demand for developing new and better WC-Co based grades. To meet the demands and to guarantee a rapid development computational thermodynamics is an important and useful tool. In this work several examples will be presented showing how the use of thermodynamic calculations support experimental work in exploring new areas of interest. Specifically the use of computational thermodynamics when inhibiting grain growth in submicron tungsten carbide, High Pressure High Temperature (HPHT) processed diamond-cemented carbide shear cutters and gradient formation in turning- and rock drill inserts will be discussed.

Key words: CALPHAD, Cemented carbides, product development.

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[O64]A multi scale modeling approach for transition metal nitride alloy coatings

B. Jansson, J. M. Ullbrand, F. Tasnádi, L. Hultman, and M. Odén

The performance of cemented carbide based cutting tools can be considerably improved by thin film coatings. Several mechanisms for the improvement can be identified such as diffusion barrier, decrease friction and increased hardness for better wear resistance. Chemically unstable thin films of transition metal nitride alloys having a homogeneous composition can be synthesized at relatively low temperatures by e.g. reactive arc sputtering. The coatings might undergo controlled precipitation hardening through spinodal decomposition by tuned heat treatment or high temperature and mechanical load application. First-principles density-functional theory (DFT) for a relatively small system (~100 atoms) can be used to solve the quantum mechanical problem combined with thermodynamic (CALPHAD) methods to model the microstructure evolution on the nm to μm scale utilizing continuum models and the phase field approach. This multi scale modeling approach has experienced certain success. However, presently the different methods used for different scales are not interfacing fully and are often treated separately. For example, DFT calculations emphasize the electronic subsystem, while atomic motions are often neglected. Classic CALPHAD models for large time and length scales often lack adequate experimental information, which is compensated by oversimplified interpolations. Examples of required input data for adequate modeling the microstructure evolution by the phase field approach that can be generated from DFT calculations are:

• Thermodynamic properties of homogenous solid solution phases.• Anisotropic elastic properties as a function of composition and pressure.• Lattice parameter as a function of composition and pressure.• Surface tension for diffuse interfaces, e.g. gradient energy.• Activation energy of diffusion.Experimental information regarding the microstructure and heat evolution is also required to tune the

phase field models and DFT calculations:• Differential scanning calorimetry to study kinetics and evolved heat in situ• X-ray diffraction (SAX/WAX) to study the kinetics of the microstructure evolution• Characterization of the microstructure by TEM and APT (atom probe tomography) after heat

treatments.The ability to model the spinodal decomposition and its effect on mechanical properties can thus be

utilized as a tool to design and to tailor coatings to desired properties.

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[O65]Challenges of Precipitation Kinetic Modelling. I. Study on

Growth Rate Models

Qing Chen

Thermo-Calc Software AB

The temporal evolution of particle size distribution is determined via a continuity equation by system thermodynamics and kinetics embodied in the nucleation rate and growth rate of different particles. Formulating appropriate models for the nucleation and growth and solving the governing equation in an efficient and robust way constitute the major challenges for the kinetic simulation of precipitation. In this presentation we focused on developing various approximations for the growth of precipitates under the diffusion controlled condition. We have implemented them in TC-PRISMA, a computational tool for kinetic simulation of precipitation in multicomponent and multiphase systems. We then applied these models to study concurrent nucleation, growth, and coarsening processes in different alloy systems, and discussed their advantages and limitations on the basis of the simulation results.

Key words: Precipitation, Thermodynamics, Kinetics, Modelling.

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[O66]Phase Equilibria at Low Temperatures (< 600 °C) and Thermodynamic

Evaluation in the Fe-base Binary Systems.

Ikuo Ohnuma, Shota Shimenouchi, Toshihiro Omori, Ryosuke Kainuma, Kiyohito Ishida

Tohoku University

In some Fe-base alloys, peculiar phase equilibria at low temperatures below 600 °C have been proposed by experimental studies and predicted by thermodynamic calculation. For instance in the Fe-Si binary system, the bcc phase exhibits two-fold ordering from the disordered A2 to the intermediately ordered B2 and further to the ordered D03 structures. In addition, miscibility gaps among these 3 phases, B2 + D03 and A2 + D03, were confirmed, which is consistent with the conventional BWG calculation. On the other hand in the Fe-Al system, even though the two-fold ordering transition is identical to the Fe-Si system, the miscibility gaps, A2 + B2 and A2 + D03, are inconsistent with the BWG prediction. Furthermore, even though phase equilibria at low temperatures in the other Fe-base binary systems, such as the Fe-Ni, Fe-Cr, etc. were also studied, precise equilibrium compositions were scattered and suspicious due to the difficulty in the low temperature equilibration. In this study, extremely deformed powders of the Fe-base alloys were equilibrated at low temperatures below 600 °C and phase equilibria were determined by a FE-EPMA (JEOL:JXA-8500F) with high special resolution (< 1 μm). Gas-atomized powders of Fe-X (X = Ni, Si, Al, Cr, etc.) were prepared and deformed extremely by converge milling method. Each powder sample was encapsulated in an evacuated quarts capsule and equilibrated at temperatures between 400 and 700 °C for various durations up to 3 months. After that, each powder sample was molded in a conductive resin, mechanically polished and finished by a vibratory polisher with 0.1 μm diamond paste. Microstructure of cross section of the powder samples was examined and equilibrium compositions were determined by the FE-EPMA with low accelerating voltage of 6 kV. Making use of the experimental findings, thermodynamic re-evaluations of the Fe-X binary systems were carried out.

Key words: Fe-base alloys, order-disorder, miscibility gap, magnetic transition, FE-EPMA.

88


Lukas, Fries and Sundman “Computational Thermodynamics, the Calphad Method”, Cambridge university press (2007)

[O67]Thermodynamic modelling of defects in U-Pu-O-C

Bo Sundman1, Christine Gueneau2, Nathalie Dupin3

1INSTN CEA/Saclay, 2DEN CEA/Saclay,

3Calcul Thermodynamique, Orcet, France

The growing interest in using more complex fuels in nuclear reactors poses several problems both in manufacturing, during operation and for extreme conditions. A thorough knowledge of the thermodynamic properties of the system is necessary to understand how to control the different transformations during processing and under varying conditions during energy production. The modelling of the defects in different oxide phases will be described using the compound energy formalism (CEF) and compared with the Wagner-Schottky model and using the Kroger-Fink notation. The effect of the defects on various thermodynamic properties like solubility and heat capacity will be described. The modelling of additions of higher actinides will be discussed.

Key words: Thermodynamics; defects; modelling; nuclear fuels; Compound Energy Formalism.

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[O68]The Ternary Ni-Sb-Sn System: Phase Diagram and Thermochemistry

Herbert Ipser, Ratikant Mishra

University of Vienna

Ternary Sb-Sn alloys are being considered as high-temperature solders where the liquidus temperature can be adjusted by varying amounts of a third element, among them also Ni. On the other hand, Ni is frequently used as substrate material in electronics. Therefore, the ternary Ni-Sb-Sn phase diagram is of high importance for lead-free electronics. The phase diagram of this ternary system was investigated, with particular emphasis on the Sn-rich corner, by X-ray powder diffraction, electron microprobe analysis and thermal analyses. A number of isothermal sections, different isopleths, as well as the liquidus projection will be presented. Partial pressures of Sb were determined by an isopiestic vapor pressure method along three sections through the ternary system, i.e. xNi/xSn = 3/1, 3/2, and 3/4. From these measurements it was possible to derive partial Gibbs energies (i.e. thermodynamic activities) of Sb, and from their temperature dependence the other partial thermodynamic properties could be obtained. All these experimental data provide an input for a CALPHAD-type optimization of the ternary Ni-Sb-Sn system, of which a very first version will be shown.

Key words: Lead-free Soldering; Ni-Sb-Sn, Phase Diagram; Ni-Sb-Sn, Thermodynamic Properties; Vapor Pressure Measurements.

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[1] J.H. Park, Calphad 31, (2007) 149. J.H. Park, Calphad 31, (2007). [2] J.H. Park, H.R. Gaye, Metall. Mater. Trans. B 39B, (2008). [3] J.H. Park, I.H. Jung, Met. Mater. Int. 15, (2009). [4] J.H. Park, H. Todoroki, ISIJ Int. 50, (2010).

[O69]Applications of Computational Thermodynamics on the Fundamental Research

on the Complex Metal-Oxide Systems

Joo Hyun Park

Materials Science and Engineering, University of Ulsan

The oxide systems for metallurgical slags and inclusions are at least ternary systems, in general. The phase equilibria including fully liquid phase and ‘solid+liquid’ coexisting area (mush zone), and thus the melting point and the solid fraction in a mush zone are of great importance not only in an understanding of the fundamental principles of metallurgical phenomena but also in an optimum design of industrial processes. However, there is still lack of reliable phase diagrams of complex oxide systems, e.g. metallurgical slags containing CaF2, ZrO2, and Cr2O3, etc., and inclusion systems containing TiOx. Thus, the computational thermodynamic package, FactSageTM, is widely used to expect the phase equilibria in metallurgical processes. Some examples of the applications of this methodology to the metallurgical reactions are as follows. The phase diagram, and mass fraction of liquid and solid compounds of the multi-component slags as well as the activity of components in a ‘liquid’ phase was calculated. Thus, a complex desulfurization behavior and a formation of intermediate compounds of the slag system are well explained. The solidification path and thus a mass fraction of solid and liquid phases of the CaO-SiO2-MgO-Al2O3-CaF2 quinary inclusion systems frequently occurred in stainless steels were calculated. Hence, the crystallization behavior of MgAl2O4 spinel phase in oxide inclusions during steelmaking and continuous casting processes was clarified. The stability diagram of the inclusion systems in the Fe-Cr-Si-Mn-Mg melts and the phase diagram of the MgO-Al2O3-TiOx ternary system was calculated. The observed inclusion composition and morphology was in good correspondence to the calculated phase equilibria of this system. Finally, the viscosity of slags is strongly affected by the composition and structure of slags, which can be modeled by newly released FactSageTM program. This could be a good guidance for designing the high temperature metallurgical processes.

Key words: Slag, inclusion, steel, phase diagram, stability diagram, FactSage, solidification, viscosity, structure.

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[1] A.D. Pelton, P. Chartrand and G. Eriksson, Metall. Mater. Trans., vol. 32A, pp. 1409-16 (2001). [2] C. Robelin and P. Chartrand, J. Chem. Thermodyn., vol. 43, pp. 377-91 (2011). [3] E. Renaud, C. Robelin, A.E. Gheribi and P. Chartrand, submitted for publication to “J. Chem. Thermodyn.” (2011).

[O70]Overview of the Molten Chlorides, Fluorides and Chloro-fluorides

Databases of the FactSage Thermochemical Software

Christian Robelin, Patrice Chartrand

Ecole Polytechnique de Montreal (CRCT)

The main salt databases currently available in the FactSage Thermochemical Software are: LiCl-NaCl-KCl-RbCl-CsCl-MgCl2-CaCl2-SrCl2-BaCl2, LiCl-NaCl-KCl-MgCl2-CaCl2-MnCl2-FeCl2

(-FeCl3)-CoCl2-NiCl2-AlCl3,NaCl-KCl-MgCl2-CaCl2-ZnCl2, and LiCl-LiF-NaCl-NaF-KCl-KF-MgCl2-MgF2-CaCl2-CaF2-SrCl2-SrF2. The liquid was modelled using the Modified Quasichemical Model in the Quadruplet Approximation [1] that evaluates coupled 1st- and 2nd-nearest-neighbour short-range order. All binary subsystems as well as all higher-order (mostly ternary and ternary reciprocal) subsystems for which experimental data were available have been considered. A complete critical evaluation of all available phase diagram and thermodynamic data (enthalpy of mixing of the liquid, EMF and vapour pressure measurements) has been performed for the condensed phases (liquid, solid solutions, stoichiometric compounds) and relevant gaseous species of the various systems, and optimized model parameters have been found. Emphasis will be put on the modelling of AlCl3-based systems, and on the recent additions of ZnCl2

[2] to the NaCl-KCl-MgCl2-CaCl2 system and of Sr2+ [3] to the Li+, Na+, K+, Mg2+, Ca2+ // Cl–, F– reciprocal system. In particular, the binary systems ACl-AlCl3 (where A = Li, Na or K) show strong negative deviations from ideality at the equimolar composition (due to short-range ordering in the liquid phase) and the binary mixtures exhibit a region of liquid-liquid immiscibility at high AlCl3 content. The existence in such melts of the AlCl4- and Al2Cl7- species was observed by Raman spectroscopy. In order to introduce two different compositions of maximum short-range-ordering near the AAlCl4 and AAl2Cl7 compositions, pure liquid aluminum chloride was modelled as a mixture of AlCl3 and Al2Cl6 (with two paired aluminum cations). The existence of a sharp minimum of solubility of MCl2 in ACl-AlCl3 melts near the equimolar composition (where M is a divalent cation such as Co2+) will also be discussed.

Key words: Molten chlorides; AlCl3; ZnCl2; Molten chloro-fluorides; SrF2; SrCl2; Salt fluxes; Thermodynamic modelling; Thermodynamic database.

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[O71]The Cryolite Database for the Hall-Heroult Alumina Reduction Process

Patrice Chartrand, Christian Robelin, Matthias Heyrman, Nagendra Tripathi

Ecole Polytechnique, Montreal

A molten Na3AlF6(cryolite)-AlF3-CaF2 solution is used in all alumina reduction smelters around the world for the production of tens of millions of tons of aluminum every year. Additives (LiF, KF, MgF2) and impurities (P, S, C, Fe, Be) play an important role in the process operation and efficiency, and they affect its environmental impacts. For the last ten years, an extensive thermodynamic database coupled with physical property databases (viscosity, density, electrical conductivity) have been developed by the authors with the support of aluminum producers. An overview of the thermodynamic database, and how it is intimately coupled with the physical property models will be shown, with examples of their applications to the Hall-Heroult process. The structure of cryolite melts and how it is taken into account in the modeling will also be discussed.

Key words: Molten fluorides; Complex ions; Thermodynamic modelling, Thermodynamic and physical-property databases; Application to aluminum production.

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[O72]Development of a thermodynamic database for Ni-containing oxide

systems for simulation of Ni extraction from laterite ores

Viktoria Prostakova1, Jeff Chen2, Eugene Jak2, Sergei A. Decterov1

1CRCT/Ecole Polytechnique of Montreal 2Pyrosearch/The University of Queensland, Australia

The present study reports the optimization of the CaO-MgO-NiO-SiO2 system. It is part of an on-going research project to develop a self-consistent thermodynamic database for nickel extraction from laterite ores. The database development is done by thermodynamic modeling which is closely related to experimental study of phase equilibria. Initially, parameters of the models are optimized to fit the experimental data collected from the literature. When there is not enough data to constrain the model parameters, or significant discrepancies in the available data are revealed, experimental measurements are initiated for temperatures and compositions which are most useful for thermodynamic modeling. The experimental procedure involves equilibration and ultra rapid quenching followed by electron probe X-ray microanalysis (EPMA) of quenched samples. Since the analysis takes place after equilibration, the changes in composition during equilibration do not affect the accuracy of the results. Tie-lines between equilibrated liquid and solid phases are measured directly, providing essential data for subsequent thermodynamic modeling. The Modified Quasichemical Model [2] is used for the slag (molten oxide) phase. The models based on the Compound Energy Formalism [3] have been developed for the olivine, spinel and pyroxene solid solutions. These physically meaningful models are based on the structure of the corresponding solution and, therefore, have good ability to predict the properties of multicomponent systems. However, accurate data in low-order sub-systems are often needed to properly constrain parameters of these models. Such data are often missing in the literature because they are of no direct importance for practical applications. A limited number of experimental measurements specifically designed to constrain the models significantly reduces the amount of work required to obtain an accurate thermodynamic description of a multicomponent system.

Key words: Thermodynamic modeling; Phase equilibria; Nickel extraction; EPMA.

[1] C.W. Bale, P. Chartrand, S. Decterov, G. Eriksson, K. Hack, R.B. Mahfoud, J. Melancon, A.D. Pelton, S. Petersen, Calphad 26 (2) (2002) 189-228. [2] A.D. Pelton, M. Blander, Metall. Trans. B 17B (1986) 805-815. [3] M. Hillert, B. Jansson, B. Sundman, Z. Metallkd. 79 (2) (1988) 81-87.

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[1] M. Hillert, Journal of Alloys and Compounds 320 (2001) 161-176. [2] A.Fernández Guillermet, in “Proceedings of the Nineth International Conference on High Temperature Materials Chemistry”, editado por K.E.Spear; The Electrochemical Society Proceedings Volume 97-39, Pennington, N.J., 1997, pp. 135-144. [3] B.P.Burton, N.Dupin, S.G.Fries, G.Grimvall, A.Fernández Guillermet, A.P.Miodownik, W.A.Oates and V.Vinograd, Zeitschrift für Metallkunde 92 (2001) pp. 514-525. [4] S.Sommadossi and A. Fernández Guillermet, Intermetallics 15 (2007) pp. 912-917. [5] S.Sommadossi, H.Troiani and A. Fernández Guillermet, Journal of Materials Science 42 (2007) pp. 9707-9712. [6] S. Ramos de Debiaggi, G.F. Cabeza, C. Deluque Toro, A. Monti, S. Sommadossi, A. Fernández Guillermet, Journal of Alloys and Compounds 509 (2011) pp.3238-3245. [7] S. Ramos de Debiaggi, G. F. Cabeza and A. Fernández Guillermet (to be published).

[O73]Gibbs Energy Assessment for Stable and Metastable Compounds:

Experiments, Phenomenology and Theory

Armando Fernández Guillermet 1,2

1 Centro Atómico Bariloche – Instituto Balseiro 8400 San Carlos de Bariloche - Río Negro - Argentina

2 CONICET

The thermodynamic modeling of binary and higher-order alloys using the Compound Energy Formalism [1] involves the evaluation of parameters representing the Gibbs energy of stable or metastable compounds. Traditionally, these parameters have been determined by fitting the model equations to experimental data, using computer optimization techniques. However, since the systems of interest are often poorly known from experiments, there has been a long-standing interest in the development of thermodynamic estimation methods to be used as a complement in the optimization procedure [2,3]. The present work is part of a long-term research line aimed at developing an integrated assessment approach based on the combination of experimental, phenomenological and theoretical (“ab initio”) methods. Specifically, the lecture will refer to research work on, i.a., transition metal carbides and nitrides, and materials of interest in the design of alloys for lead-free diffusion soldering techniques [4-7].

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[O74]A design driven Superalloy development approach

Nils Warnken, Roger C Reed

Univerisity of Birmingham

The development of Ni-base superalloys over the last few decades has led to alloys with remarkable complexity; many alloy specifications comprise about 10 major alloying elements. It becomes obvious that systematic experimental studies, leading to new alloy compositions are quite complicated, as these would have to include thousands of alloys. As an alternative approach, design rules are applied to identify promising superalloy compositions. These simple rules characterise the most important properties, such as creep resistance, microstructural stability, oxidation resistance, manufacturability, density and cost. In order to determine these, CALPHAD type and other calculations are performed on a very large number - of the order of 1,000,000 - of alloy compositions. From these results a few ideal compositions are selected according to design specifications which are suitable for either aeroengine blades or disk alloys or as blade alloys for industrial gas turbines. Future enhancements of the method are discussed.

Key words: Superalloy, Alloy development, Properties, Manufacturability.

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[O75]Interfacial Free Energies from Data on Coarsening Plus Assessments of

Gibbs Free Energies of Mixing in Ni-Base g/g ′ Alloys

Alan J. Ardell

Metals and Metallic Nanostructures Program, National Science Foundation Arlington, VA 22230, USA

Data on coarsening of g ′-type precipitates (Ni3X, with the L12 crystal structure) in a variety of binary and ternary Ni-base alloys are re-evaluated in light of recent (TIDC) and classical (LSW) theories of coarsening, with the objective of ascertaining the best values possible of interfacial free energies, σ, of the precipitate/matrix interfaces. The re-evaluations include fitting of the particle size distributions, reanalyzing available data on the kinetics of particle growth and kinetics of solute depletion, and using thermodynamic assessments of the binary alloy phase diagrams to calculate curvatures of the Gibbs free energies of mixing. The product of the work is 2 sets of interfacial free energies, one set for the analysis using the recent TIDC theory and the other for the analysis using the classical LSW theory. The TIDC-based analysis yields lower values of σ by about a factor of 2/3. All the interfacial energies are considerably larger, by factors ranging from ~4 to 10, than those previously reported, which were nearly all calculated from data on coarsening assuming ideal-solution thermodynamics. In the TIDC theory the width of the interface, δ, is allowed to increase with particle size, r. A simple equation relating σ to the ratio of the gradient energy and δ is used to show that σ can remain constant even though δ increases with r. The magnitudes of σ in the different alloys are discussed in the context of qualitative considerations of bonding in the various alloys. The results on the important Ni-Al alloy system are compared with the predictions of various atomistic simulations of the energy of the Ni3Al/Ni-Al interface.

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No. 2011CB610401) and the National Natural Science Foundation of China (Grant Nos. 50721003 and 50831007) is greatly acknowledged.

[O76]Phase-field simulation of grain growth in anisotropic systems

Dan Cai1, Lijun Zhang1,2, Yong Du1,*


2 Interdisciplinary Centre for Advanced Materials Simulation (ICAMS), Ruhr-Universität Bochum, 44801 Bochum, Germany


The phase-field method has proven to be a powerful tool for grain growth and related phenomena during the past decades. With the available grain boundary energy and mobility plus thermodynamic properties, the evolution of grain growth can be simulated in 2D and 3D using the phase-field method, and the corresponding macroscopic parameters, i.e. the grain size and the grain orientation distributions, are thus obtained. Considering the great challenge to perform quantitative simulation of grain growth in anisotropic systems, a phase-field code based on the continuum-field approach was developed in the present work. The misorientation between neighboring grains and the grain boundary inclination were also taken into account. With grain orientations randomly distributed, the phase-field simulation of grain growth evolution in an anisotropic system was performed using the present phase-field code, as shown in Fig. 1. Four types of triple junctions between small/large angle misorientation grains can be predicted. The present work also demonstrates that the boundaries between large angle misorientation grains combine with each other or disappear much faster than other kinds of boundaries. In order to quantitatively simulate the austenite grain growth in the Fe-C system, the Mont-Carlo and Molecular Dynamic simulations were made to compute the grain boundary energy. With the computed boundary energy, the evolution of austenite grain growth in the Fe-C system was simulated using the present phase-field code, and the simulated results were compared with the corresponding experimental data. In addition, the pinning effect was also investigated in the present work.

Figure 1. Phase-field simulation of grain growth evolution in an anisotropic system using the present phase-field code. Black lines are the grain boundaries with large angle misorientations,

while grey ones the boundaries with small angle misorientations.

Acknowledgements: The financial support from the National Basic Research Program of China (Grant

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[O77]The effect of elastic anisotropy on the spinodal decomposition in

(Ti,Al)N - a phase field study

Jennifer M. Ullbrand1, Bo Jansson1, Ferenc Tasnádi2, Lars Hultman3, Magnus Odén1

1Nanostructured materials, IFM, Linköping University, 2Theoretical Physics, IFM, Linköping University,

3Thin Film Physics, IFM, Linköping University

The phase field approach has been used to solve the Cahn-Hilliard equations for a number of (AB)- model systems, but few results are published on real material systems and compared to experiments. In this study the phase field method is used to simulate spinodal decomposition in the (Ti,Al)N system. (Ti,Al)N thin films are of great industrial interest as hard wear protective coatings, e.g.on inserts for metal cutting. Coatings with compositions inside the spinodal can be synthesized at low temperatures by physical vapor deposition processes. The temperature at the edge can reach up to 1000°C during cutting and the coating will then decompose. Thus, by proper aging of the coating a considerable hardening effect can be achieved during application. The variation of lattice parameter and elastic properties with composition strongly affect the microstructure evolution during the spinodal decomposition. In order to appropriately address (Ti,Al)N alloys, enthalpy of mixing, the elastic compliance tensor and the lattice parameter, determined by first-principles density-functional theory (DFT) calculations, are used as input parameters. The elastic problem is solved exactly in every time step and the atomic mobilities are adjusted by comparison with experiments. At compositions above 40% AlN the microstructure exhibits nm-sized domains with preferred growth directions in the elastically compliant directions . At AlN contents below 40% where the elastic anisotropy is less pronounced spherical domains are instead formed. The initiation of the spinodal decomposition is notably slower when the composition is displaced from the center of the miscibility gap towards lower amounts of AlN. In addition, the evolved modulation in elastic properties itself slows down the decomposition.The origins of the observed kinetic differences are discussed and the microstructure evolution is compared to experimental observations by e.g. scanning transmission electron microscopy.

Key words: Spinodal decomposition, Phase Field, (TiAl)N, Elacticity.

99


[1] S. Decterov, A. Pelton, Metallurgical and Materials Transactions B 30 (4) (1999) 661-669. [2] P. Waldner, Internal Report, Centre for Research in Computational Thermochemistry Montreal, 2007. [3] A.D. Pelton, M. Blander, Metallurgical transactions. B, Process metallurgy 17 B (Compendex) (1986) 805-815. [4] M. Hillert, J. Alloys Compd. 320 (2) (2001) 161-176.

[O78]Thermodynamic database for copper smelting and converting

Denis Shishin1, Christopher Bale1, Eugene Jak2, Sergei A. Decterov1

1CRCT/Ecole Polytechnique of Montreal 2Pyrosearch/The University of Queensland, Australia

A thermodynamic database for copper smelting and converting developed previously [1, 2] has been further improved in the present work. The most important phases are matte (liquid sulfide), slag (liquid oxide), liquid metal, gas and oxide and sulfide solid solutions. Liquid metal and matte are modeled as one extended solution, but the slag is described as a separate solution. The core chemical system is Cu-Ca-Fe-Al-Mg-O-Si-S. The database also includes important minor elements such as Zn and Pb. The strong short range ordering in liquid solutions is taken into account by using the Modified Quasichemical Model [3]. The models relating the structure and thermodynamic properties of solid solutions have been developed within the framework of the Compound Energy Formalism [4]. The goal of the present study was to add oxygen, lead and zinc into the combined metal - matte liquid solution. This solution must describe the experimental data on the solubility of oxygen in both liquid metal and matte. It must also be consistent with the slag to reproduce the important metal - matte - slag equilibria. The developed database in combination with the FactSage thermochemical software can be used to calculate phase and chemical equilibria of interest for the production of copper. An example of its application to the real industrial process will be given.

Key words: Quasichemical model, matte, blister copper, copper smelting, copper converting, FactSage.

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Abstracts: Oral Presentations, May 27 (Friday)

Experiments and databases

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[O79]Progress in magnesium alloy database development

Rainer Schmid-Fetzer, Joachim Groebner, Artem Kozlov, Milan Hampl

Clausthal University of Technology

New classes of magnesium materials with promising property profiles have been developed in recent years. The transfer of interest from classical alloy systems like AZ, AM and ZK to new innovative classes forming LPSO and related phases has opened a new field of materials with high strength, increased ductility and high fracture toughness. Mg-RE based alloys and Mg-Zn-RE alloys, including Y, play a key role in these new classes of alloys. Progress in development of our thermodynamic Mg alloy database in that direction is reported, with examples of phase formation in as-cast and heat treated alloys. In addition, the erroneous description of Mg-hcp and Zn-hcp, which spread from the COST507 database to other databases, is revealed. Not only the description as two separate phases, hcp_A3 and hcp_Zn, but also the peculiar lattice stabilities is considered unrealistic. A remedy for that erroneous description is presented for Mg-Zn and related multicomponent systems.

Key words: Mg-alloys, database, application, Mg-RE-Zn-Y.

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[O80]The Mg-Cu-Ni-Y quaternary system: thermodynamic modeling

coupled with key experiments

Mamoun Medraj1, Mohammad Mezbahul-Islam1, Elhachmi Essadiqi2

1Concordia University 2MTL - CANMET

Mg based alloys provide a promising candidate for bulk metallic glass which has high mechanical strength and good corrosion resistance. Among these alloys, the Mg-Cu-Y system has the largest super-cooled liquid region. Also, the Mg-Ni-Y system has been found to be a potential candidate for the Ni-Metal hydride batteries. These batteries are supposed to replace the existing Ni/Cd rechargeable batteries due to environment concerns. Hence, a sound description of the Mg-Cu-Ni-Y quaternary system is essential. A thorough review and critical evaluation of phase equilibria and thermodynamic data of the phases in the Mg-Cu-Y, Mg-Ni-Y, Mg-Cu-Ni and Cu-Ni-Y and their constituent binary systems have been performed over the entire composition range from room temperature to above the liquidus. These systems are being modeled for the first time using the modified quasichemical model for the liquid phase to account for the presence of the short-range ordering properly. The Gibbs energies of the different phases have been modeled, and the optimal model parameters that reproduce all the experimental data simultaneously within experimental error limits have been obtained. Diffusion couples and key alloys are used to verify the calculated ternary systems. The alloys for diffusion couples and key experiments were prepared from pure metals (Mg-99.8 wt.%, Ni-99.9 wt.%, Cu-99 wt.%, Y wt.99.9%). Some of the samples have also been prepared using arc melting or induction melting furnaces. New ternary phases have been observed and their crystallographic data and homogeneity ranges have been identified using SEM/EPMA and XRD. Also, DSC has been used to determine the melting temperature of the key alloys. The calculated phase diagrams are compared with the current experimental results.

Key words: Diffusion couples, key alloys, XRD, EPMA, SEM, DSC.

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[1] Y. Kawamura, K. Hayashi, A. Inoue and T. Matsumoto: Mater. Trans. 42 (2001), 1172. [2] A. Inoue, Y. Kawamura, M. Matsushita, K. Hayashi and J. Koike: J. Mater. Res. 16 (2001), 1894. [3] E. Abe, Y. Kawamura, K. Hayashi and A. Inoue: Acta Mater. 50 (2002), 3845.

[O81]Experimental study on the long period ordered (LPO) phase

in magnesium alloys

M Jiang, HX Li, YP Ren, SM Hao

Key Laboratory for Anisotropy and Texture of Materials, Ministry of Education, Northeastern University, Shenyang 110819, China

Mg-base alloys have been attracted as lightweight and high strength structural materials because of their low density, high specific strength and stiffness. It has been shown that an Mg97Zn1Y2 (at. %) alloy, made through rapidly solidified powder metallurgy (RS P/M) processing, reveals excellent mechanical properties including maximum tensile yield strength 610 MPa and elongation 5% at room temperature [1,2]. It has been proved that a long period ordered (LPO) structure is formed in the alloy, with a stacking sequence of ABCBCB’, where A and B’ layers are significantly enriched by Zn and Y [3,4]. The high-strength of the Mg97Zn1Y2 alloy is due to not only a grain refinement through RS P/M, but also to the LPO phase in aMg grain. Since then more attentions have been paid to the LPO phase in the Mg-based alloys. It has been known that the LPO phase can form in Mg-TM-RE (TM = Cu, Ni, or Zn; RE = rare earth metals) alloys [5,6]. As a strengthening phase in Mg-based alloys, thermodynamic stability, phase composition and volume fraction are all important information for alloy design. However, the phase diagram information for the Mg-TM-RE systems is very limited. In this work, a systematic experimental study has been performed to the Mg-TM (TM=Cu, Ni, Zn)-RE (RE=Y, Gd) alloys. It has been proved that the LPO phase is stable in all these systems with limited solubility ranges of Cu, Ni, Zn, Y and Gd. The equilibrium compositions of the LPO phase have been determined accurately, which are different from the earlier reports. Ideal TM/RE ratios to get the LPO phase, which are important for the composition design of the LPO Mg-based alloys, have been obtained. Phase relationships concerning the LPO phase, as well as the phase diagrams in the Mg-rich region of the Mg-TM-RE ternary systems have been established.

Key words: long period ordered phase, Mg-TM-RE, phase equilibrium.

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[O82]The COST MP0602 Thermodynamic Database for High-Temperature

Lead-free Solders

Ales Kroupa1, Alan Dinsdale2, Andy Watson3, Jan Vrestal4, Adela Zemanova1, Pavel Broz4

1 Institute of Physics of Materials, The Academy of Sciences of the Czech Republic, Brno, Czech Republic 2 The National Physical Laboratory, Teddington, Middx., TW11 0LW, UK

3 Institute for Materials Research, University of Leeds, Leeds LS2 9JT, U.K. 4Department of Chemistry, Masaryk University, Brno, Czech Republic

COST Action MP0602 entitled “HISOLD – Advanced Solder Materials for High Temperature“ ; has as its main objective, according to the Memorandum of Understanding, “…to increase the fundamental knowledge of the crucial properties of alloys that can be used as environmentally friendly alternatives to high-temperature solders. The aim is to identify promising materials with a set of suitable properties, such as melting point, wettability and surface tension, which will allow them to be used successfully in a variety of industrial applications. Furthermore, health and economic issues must be taken into account during the evaluation in addition to the physical, chemical and mechanical behaviour.” The Action started officially on May 15, 2007, and its official end is May 15, 2011. 25 countries signed the Memorandum of Understanding. Of these, 22 countries involving approx. 60 research teams were actively engaged in research as part of COST MP0602. One of the main outcomes of the Action, closely related to the topic of the CALPHAD conference, is a self-consistent thermodynamic database developed for high temperature lead-free solders (approx. 260-350°C) and their interaction with selected substrate materials. This database is based on the existing 11 component SOLDERS database (itself a product of the COST 531 Action) with additional elements and systems, important for HT solders. Currently the database contains 18 elements (Ag, Al, Au, Bi, Co, Cu, Ga, Ge, Mg, Ni, P, Pb, Pd, Sb, Si, Sn, Ti, Zn), but not all binary system assessments are included. The database has been tested extensively using MTDATA, ThermoCalc and Pandat to ensure portability between different platforms. Experimental thermodynamic and phase equilibrium data and thermodynamic assessments generated within the action have been included where appropriate.

This work was supported by the Czech Ministry of Education, Youth and Sports projects No. OC08053 and OC09010.

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[O83]EMF Measurements in the Liquid Ag-Bi-Cu-Sn Lead-free Solder Alloys

Leszek Zabdyr, Grzegorz Garzel

Polish Academy of Sciences

Electromotive force measurements were carried out in the liquid quaternary Ag-Bi-Cu-Sn alloys by the use of solid oxide electrolyte galvanic cells with air reference electrode. Experiments were made within temperature interval: 950 - 1300K along four composition paths of constant ratios: XAg : XBi : XCu = 1, XAg : (XBi : XCu) = 3/2, XBi : (XAg : XCu) = 3/2 and XCu : (XAg : XBi) = 3/2 and tin content changing from 0.1 to 0.9 mole fraction, every 0.1. All the results were approximated by straight line equations: EMF vs T, and tin activities were then calculated in two arbitrary temperatures. Results were presented by graphs and listed in tables. Unusual activity curve for XBi : (XAg : XCu) = 3/2 composition path was most probably caused by miscibility gap detected earlier in Bi-Cu-Sn ternary liquid alloys. Results will be used along with planned calorimetric measurement results for optimization of the quaternary system under accord by CALPHAD approach.

Key words: Lead-free solders, emf, thermodynamic properties.

* Presenting author e-mail: [email protected]

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[O84]Open CALPHAD - software and databases

Ursula R. Kattner1, Bo Sundman2, Mauro Palumbo3, Suzana G Fries3

1National Institute of Standards and Technology, Gaithersburg, MD,, USA 2INSTN CEA, Saclay France

3ICAMS, STKS, Ruhr University Bochum, Bochum, Germany

Calphad type databases and various application software have become a necessary tool for industrial development of new materials and alloys. In particular for applications in phase transformations and thus the simulation of microstructures and materials properties the thermodynamic and kinetic databases have now gained an established position. But this is also a field of intense research as new data and first principle techniques provide new ideas for models as well as thermodynamic data in composition ranges not accessible by experimental techniques. Thus there is a need for constant revision of databases and software to include these ideas and data. Unfortunately the companies providing the software and databases are too small to carry out heavy research projects. Since today all major thermodynamic software and databases are commercial this leaves very little opportunities for researchers to develop and test new ideas. There are some minor open source software packages available for Calphad applications but the Sapiens project at ICAMS in Bochum, Germany, has taken the initiative to start developing open software with full modeling facilities and provide this to the scientific community [1]. It is called Open Calphad and it is still in the cradle but will be made available on the web, without cost, either as free or open software, making it possible to modify the source code and to implement it in any other software. This facility has already been utilized for evaluating new heat capacity models (see presentation by Mauro Palumbo). This software, in part utilizing code that was developed by Leo Lukas [2], is written in Fortran 90 with a command driven user interface and a software interface based on the TQ definition [3]. We hope that several programmers will be interested to provide interfaces to other languages as well as a more advanced GUI.

Acknowledgement: ThyssenKrupp AG, Salzgitter Mannesmann Forschung GmbH, Robert Bosch GmbH, Bayer Materials Science AG, Bayer Technology Services GmbH, Benteler Stahl/Rohr AG, state of North Rhine-Westphalia and European Commission in the framework of the European Regional Development Fund (ERDF).

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[O85]Thermodynamic evaluation of the Ti-Al-C system

Bengt Hallstedt

Materials Chemistry, RWTH Aachen University, Aachen, Germany

The Ti-Al-C system is of interest for several applications. The intermetallic γ-TiAl (L10) is a candidate light-weight material for high temperature applications. It normally contains a small amount of carbon, which precipitates as Ti3AlC on short term annealing and as Ti2AlC after longer times. Ti3AlC has the perovskite structure, i.e. L12 with the central interstitial site filled with C. There is a phase with this structure also in e.g. the Fe-Al-C system (Fe3AlC) where it is called κ carbide. Ti2AlC and Ti3AlC2 belong to a group of phases called MAX-phases. The MAX-phases have layered crystal structures, sometimes called nano-laminates, and show properties intermediate between metallic and ceramic materials. This makes them attractive for a number of applications. All three ternary carbides show considerable non-stoichiometry with respect to carbon. Here a thermodynamic evaluation of the Ti-Al-C system is presented based on evaluations of the three binary sub-systems from literature. Experimental data on the carbon solubility in the intermetallic Ti-Al phases and the stoichiometry of the ternary carbides are in some cases strongly contradictory. For Ti2AlC first-principles DFT calculations were used to study the energies of some of the possible defects, including C vacancies. The focus of the presentation will be on basic modelling issues and the selection of experimental data.

Key words: Ti-Al-C, thermodynamic evaluation, phase diagrams, ternary system, Calphad.

108


[1] Z. K. Liu, “First-Principles Calculations and CALPHAD Modeling of Thermodynamics,” Journal of Phase Equilibria and Diffusion, Vol.30, 2009, 517-534. [2] Y. Wang, S. Curtarolo, C. Jiang, R. Arroyave, T. Wang, G. Ceder, L. Q. Chen and Z. K. Liu, “Ab initio lattice stability in comparison with CALPHAD lattice stability,” Calphad-Computer Coupling of Phase Diagrams and Thermochemistry, Vol.28, 2004, 79-90. [3] P. E. A. Turchi, I. A. Abrikosov, B. Burton, S. G. Fries, G. Grimvalle, L. Kaufman, P. Korzhavyi, V. R. Manga, M. Ohno, A. Pisch, A. Scott and W. Q. Zhang, “Interface between quantum-mechanical-based approaches, experiments, and CALPHAD methodology,” Calphad-Computer Coupling of Phase Diagrams and Thermochemistry, Vol.31, 2007, 4-27. [4] V. Ozolins, “First-Principles Calculations of Free Energies of Unstable Phases: The Case of fcc W,” Physical Review Letters, Vol.102, 2009, 065702. [5] Z. G. Mei, S. L. Shang, Y. Wang, Z. K. Liu and V. Ozolins, “Ab initio study of hcp-to-bcc phase transition in Ti,” To be submitted, 2011. [6] V. Ozolins, “First-Principles Calculations of Free Energies of bcc and hcp Zr,” To be submitted, 2011.

[O86]Lattice stability by ab initio molecular dynamic simulations

Zi-Kui Liu1, Zhi-Gang Mei1, Vidvuds Ozolins2

1The Pennsylvania State University 2University of California, Los Angeles

Thermodynamic modeling based on the CALPHAD technique relies on available thermochemical and phase equilibrium data, and the lattice stability is its foundation. First-principles calculations based on density functional theory are becoming a powerful approach in providing thermochemical data in addition to experimental investigations [1]. However, it remains challenging in predicting the lattice stabilities of unstable phases from first-principles calculations [2-3]. The recent breakthrough demonstrated the applicability of ab initio molecular dynamics (AIMD) in predicting the lattice stability of unstable fcc W [4]. Furthermore, it was shown that various lattice stability values proposed in the literature could be correlated through the relative contributions of enthalpy and entropy to lattice stability. In this presentation, our recent efforts in predicting the enthalpy and entropy contributions to lattice stability of Ti [5] and Zr [6] will be discussed.

Key words: Lattice stability, first-principles calculations, ab initio molecular dynamics, AIMD.

109


[O87]Thermodynamic Properties of the Au-Sb-Sn and Au-Sb system

M Hindler and A. Mikula

Institut für Anorganische Chemie/Materialchemie, Universität Wien, Vienna, Austria e-mail: [email protected]

Some Au-Sb-Sn alloys might become useful to replace lead containing solders at temperatures between 300 and 450 °C. We determined the thermodynamic properties of such alloys in the liquid state with an emf method, using a liquid electrolyte and with calorimetric measurements. The results of both experiments are in excellent agreement with each other. See Fig.1.

x, Sn

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

∆H (J

/mol

)

-9000

-8000

-7000

-6000

-5000

-4000

-3000

-2000

-1000

0

Au:Sb 2:1 EMF at 873 KAu:Sb 1:1 EMF at 873 KAu:Sb 1:2 EMF at 873 KAu:Sb 2:1 Calorimetry at 873 KAu:Sb 1:1 Calorimetry at 873 KAu:Sb 1:2 Calorimetry at 873 K

In order to calculate the integral quantities with the Gibbs-Duhem equation the thermodynamic data of the binary systems, in our case the Au-Sb system has to be known. Since we found only one set of data in the literature we had to use them. As it turned out with this set of data we could not get reliable results for the integration. So we had to re-measure the properties of the Au-Sb system. The problem for the emf measurements in this system was, as it has already been pointed out by the previous author, the high vapour pressure of SbCl3. We prepared the KCl-LiCl electrolyte, powdered it and mixed it with SbCl3. The mixture was sealed in a tube and heated in a furnace for a longer time at 110oC.The reason was to form a stable compound of LiCl and SbCl3 This was used as a stable electrolyte for the emf measurements. The results of the Au-Ab measurements fit vers well into the results of the ternary system.

110


[1] J. H. Gladstone, Quart. Journ. of the Chem. Soc., 6 (1854) 106 [2] M. Le Chatelier, Bull. soc. chim., 47 (1887) 300 [3] K. Kubierschky, Hist., (1902) 404-413 [4] J. H. van’t Hoff and H. Barschall, Sitzungsber. K. Preuss. Akad. Wiss., 18 (1903) 359-371. [5] E. Jänecke, Z. Phys. Chem. Stoechiom. Verwandschaftsl., 64 [3] (1908) 343-356. [6] R. Nacken, Zentralbl. Mineral., Geol. Palaeontol., (1910) 262-271 [7] H. Müller, Neues Jahrb. Mineral., Geol. Palaeontol., Beilageband 30, (1910) 1-54. [8] W. Grahmann, Zeitschrift für Anorganische Chemie, 81 (1913) 257-314. [9] W. Eysel, American Mineralogist, 58 [7-8] (1973) 736 [10] J. M. Sangster and A. D. Pelton in “Critical Coupled Evaluation of Phase Diagrams and Thermodynamic Properties of Binary and Ternary Alkali Salt Systems”, Special Report to the Phase Equilibria Program, Part B: Evaluations for 54 common-ion binary systems involving (Li, Na, K) and (F, Cl, OH, NO3, CO3, SO4), American Ceramic Society; Westerville, Ohio; (1987) pp. 4-231. [11] N. Mofaddel, R. Bouaziz and M. Mayer, Thermochimica Acta, 185 [1] (1991) 141-153

[O88]Experimental Studies and Re-assessment of the Quasi-binary Systems containing

the Sulfates of Sodium, Potassium, and Calcium by Differential Thermal Analysis and X-Ray Diffraction

D. Kobertz, M. Müller

Forschungszentrum Jülich, IEK-2, D-52425 Jülich, Germany, email: [email protected]

The combustion of lignite containing high amounts of sulfur, calcium, potassium, and sodium induces the formation of sulfatic depositions and corrosion related processes on refractory metal and ceramic material. These depositions diminish the heat conductance and their spalling leads to damages in the power plant. The mechanisms for the formation of these conglomerations are initiated by low-melting or related to adhesive sulfatic phases. Limitation of fossil fuel resources requires an increase of the efficiency of power plants by using combined cycle power systems. The pressurized pulverized coal combustion (PPCC) combined cycle is a coal fired combined cycle concept which is able to achieve efficiencies in excess of 53%. The direct use of the hot flue gas for driving a gas turbine requires a hot gas cleanup to achieve corrosion prevention of the turbine blading. Hot corrosion on turbine blading is initiated by deposition or condensation of corrosive species like alkali sulfates and dependent on concentrations of alkalis in the hot flue gas. Type I hot corrosion is caused by the formation of liquid Na2SO4 above its melting point (884 °C). Type II hot corrosion is caused by the formation of an eutectic melt of NiSO4 and Na2SO4 above 671 °C. NiSO4 itself is formed by the reaction of the oxide scale of Ni base alloys in blading with SO3 in dependence of the SO3 partial pressure in the hot flue gas. The motivation of our studies is to understand the aforementioned alkali sulfate related processes under applied conditions and accrued phases. Multi component sulfatic systems can only be really understood after comprehending the basic binary sub-systems. This work includes the experimental studies of the three sub-systems Na2SO4 - CaSO4, K2SO4 - CaSO4, and Na2SO4 - K2SO4 since there are variant and even contradictory results and interpretations in the literature (e.g. [1-11]). Differential Thermal Analysis (DTA) with simultaneous Thermo Gravimetry (TG) as well as X-ray Diffraction (XRD) measurements were done both to achieve the transition temperatures and the phase compositions in the sulfatic systems.

111


List of Poster PresentationsAll posters will be on display starting on monday morning, until friday morning

Applications to process and materials design and development

[P1] Antonio J Ramirez, Jimy Unfried S Design of a Ductility-Dip Cracking Resistant Ni-Cr-Fe Alloy

[P2] Ashutosh S. Gandhi, Abhiram Muralidhar, K.C. Hari Kumar Effect of surface energy on the zirconia-yttria phase diagram: a CALPHAD approach

[P3] Jean-Christophe Dumas, Jean-Paul Piron, Chantal Martial Evaluation of the Chemical Composition of Irradiated Mixed Carbide Fuel

[P4] Fábio Dian Murari, André Luiz Vasconcellos da Costa e Silva, Roberto Ribeiro de Avillez Effect of Boron on the Microstructure and Mechanical Properties of Cold Rolled Multiphase Steels

[P5] Fiquiri Hodaj, O. Mailliart, V. Chaumat The role of atmosphere on the interfacial interactions between molten oxide glasses and silicon carbide

[P6] Humberto Luiz Gama de Magalhães, Carlos Antônio da Silva, Andre Luiz Vasconcelos da Costa e Silva Title Improve cleanliness of SAE 1045 Al-killed steel grade with applied in the automobilistic industry,

using computational thermodynamic

[P7] In Gee Kim, Jee Yong Lee Computational Thermodynamics and Spheroidisation of Bearing Steels

[P8] José Britti Bacalhau, Eduardo Netto de Souza, Alexandre Bellegard Farina, Celso Antonio Barbosa Thermodynamic Simulation Of Nitrogen And Manganese Contents In Delta Ferrite Formation Of Plastic

Mold Stainless Steel

[P9] Marcos Flavio de Campos, Shimeni Baptista Ribeiro, Jefferson Fabricio Cardoso Lins, Alexandre Bellegard Farina

Microstructural Evolution in the Aging of Inconel 718

[P10] Meire Guimarães Lage, André Luiz V. da Costa e Silva Evaluating segregation in HSLA steels using computational thermodynamics

[P11] M. Ba, A. Dia, P. Berthod, L. Aranda, Th. Schweitzer, P. Villeger Experimental and thermodynamic study of ternary Fe-30Cr-xC carbon-rich alloys with x varying from

2.5 to 5.0wt.%

[P12] Patrice Berthod Thermodynamic calculations used for characterizing the sub-surfaces changes induced by high temperature

oxidation for carbides-reinforced alloys

[P13] Rodrigo Freitas Guimarães, Hélio Cordeira de Miranda, Hamilton Ferreira Gomes de Abreu, Fernando Henrique Costa Sabóia

The effect of Cr and Mo in the formation of intermetallic phases

[P14] Rogério Navarro Correia de Siqueira, Roberto Ribeiro de Avillez, Eduardo de Albuquerque Brocchi Chlorination of vanadium oxide under the presence of graphite

[P15] Takashi Maehsima, Kouji Tanaka, Tadashi Ohshima and Hisaaki Takao Prediction of liquid phase behavior during the rapid transient liquid phase bonding process of steel using

cementite filler metals

112


[P16] V. Lutsyk, A. Zelenaya “Wrong and Useful” Models of SiO2-CaO-Al2O3 T-x-y Diagram

[P17] W. V. Bielefeldt, A. C. F. Vilela Thermodynamic analysis of the inclusions formation in steels for the automotive industry

CALPHAD assessments

[P18] Adela Zemanova, Ales Kroupa, Ratikant Mishra, Herbert Ipser, Hans Flandorfer Thermodynamic Assessment of the Ni-Sn-X (X=In, Sb) Ternary Systems

[P19] Ales Kroupa, Adela Zemanova, Dominik Legut The Study of Z-Phase in Ternary Cr-Nb-N and Cr-V-N Systems

[P20] Bonnie Lindahl, Malin Selleby Diffusion multiples for subsystems within the Fe-Al-C-Mn system

[P21] Changjun Wu, Xuping Su, Jianhua Wang, Ya Liu, Haoping Peng, Hao Tu First-principles calculations and thermodynamic assessment of the Te-Zr system

[P22] Xin Ren, Changrong Li, Zhenmin Du, Cuiping Guo, Sicheng Chen Thermodynamic Modeling of the Ba-Mg binary system

[P23] Miao Liu, Changrong Li,Zhenmin Du, Cuiping Guo, Chunju Niu Thermodynamic modeling of the Ge-La binary system

[P24] D. Kapush, K. Korniyenko, V. Petyuch, T. Velikanova, V. Shemet, B. Grushko Experimental Study of the Al-Ni-Pt Alloy System

[P25] E. R. Pinatel, M. Palumbo, P. Rizzi, M. Baricco Thermodynamic modelling of the LaNi(5-x)AlxHy (0< x < y)

[P26] Galina Jelkina, Lidong Teng, Bo Björkman Effect of Basicity on the Chromium Partition in CaO-MgO-SiO2-Cr2O3 Synthetic Slag at 1873 K

[P27] Guoxing Huang, Haiying Qi, Libin Liu, Zhanpeng Jin Thermodynamic assessment of Ca-Cu-Mg sytem

[P28] Hongwei Yang, Yijun Wang, Dongping Tao Application of the molecular interaction volume model to Phase diagram calculations of Fe-Ni and Fe-Co systems

[P29] K.C. Hari Kumar, Suddhasattwa Ghosh, B. Prabhakara Reddy, K. Nagarajan, P.R. Vasudeva Rao Thermodynamic assessment of LiCl-UCl3 and KCl-UCl3 binary systems by coupling CALPHAD and

first principles calculations

[P30] Libin Liu, Ligang Zhang, Hong Bo, Zhanpeng Jin Investigation of the phase diagrams and microstructure evolution of Al-Cu-RE alloys

[P31] Liling Jin, Youn-Bae Kang, Patrice Chartrand, Aimen Gheribi, Dmytro kevorkov, Mamoun Medraj Modeling of Thermodynamic Properties and Phase Equilibria in Mg-Al-Mischmetal Systems

[P32] Luiz Eleno, Márcio Gustavo di Vernieri Cuppari, Cláudio G. Schön Experimental investigation and thermodynamic modelling of the Fe-Cr-Mo-C system

[P33] Marcos Flavio de Campos, Alexandre Bellegard Farina Thermodynamic Modeling of the Binary System Co-Sm

[P34] Aurore Mascaro, Jean-Marc Joubert, Caroline Toffolon-Masclet, Caroline Raepsaet Experimental Study and Thermodynamic Assessment of the ER-H Binary System

113


[P35] Mohamed El Guendouzi, Rachid Azougen, S. Mohammed Aboufaris E., Ihssane Hamdouny Prediction of Solubility from the Water Activities in the mixed Aqueous Solutions YCl2 + Y’Cl2 + H2O

with Y’; Y ≡ Mg2+; Ca2+; or Ba2+

[P36] R. Novakovic Diffusion bonding in the Ag-Cu system

[P37] Shih-kang Lin, Dane Morgan Coupling compound energy formalism CALPHAD modeling with first principle calculation for ionic materials

[P38] Ivanov M.I., Berezutsky V.V., Shevchenko M.O., Kudin V.G., Sudavtsova V.S. Thermodynamic properties of the liquid alloys of the Al-Ln binary systems

[P39] M.O. Shevchenko, Yu.V.Fartushna, V.G. Kudin, V.S. Sudavtsova, M.V. Bulanova Thermodynamic Properties of Liquid Ti-Dy Alloys

[P40] Vaajamo Iina, Taskinen Pekka Thermodynamic Assessments of the [Co,Cr,Fe,Ni]-Pb Binary Systems

[P41] Wang Fuming, Wang Haitao, Li Changrong Control on Low Melting Point Area In CaO-SiO2-Al2O3-MnO System

[P42] Xu Fang, Kai Li, Dongdong Zhao, Yong Du Precipitation sequence of Al-Mg-Si-(Cu) alloys and its verification by first-principles calculations

[P43] Yan Zhong, Huai-Ying Zhou, Chao-Hao Hu, Shun-Kang Pan Phase relationship in the Tb-Fe-Cr ternary system at 600 °C

[P44] Yingbiao Peng, Yong Du, Honghui Xu, Peisheng Wang, Chunsheng Sha Experimental investigation and thermodynamic calculation of the Mg-Ni-Zn System

[P45] Li Chen, Yong Du, Keke Chang, Bing Yang, Wei Pan, Yingbiao Peng Microstructure and mechanical properties of TiAlN/TiN nano-multilayer coating

[P46] Zhenmin Du, Cuiping Guo, Mei Li, Changrong Li A thermodynamic modeling of the Pd−Ti system

[P47] Zhenmin Du, Dongxian Lü, Cuiping Guo, Changrong Li Thermodynamic description of the Mg-Sn-Y system

[P48] Jinming Liu, Cuiping Guo, Changrong Li, Zhenmin Du Thermodynamic re-assessment of the Ni–Sn system

[P49] Zi-Kui Liu, Chelsey Zacherl, ShunLi Shang, Yi Wang Predicting diffusion coefficients in magnetic phases by first-principles methodologies

Database development

[P50] A. Costa e Silva, M. A. da Cunha, L.N.A. Vieira, F. Rizzo The Thermodynamics of Aluminum Nitride Precipitation in Steels Revisited

[P51] A. Costa e Silva, A.Q. Bracarense, E.C.P. Pessoa, M. Monteiro, R. Avillez, F. Rizzo, V.R.Santos Thermodynamics of flux behavior in steel welding with focus on hydrogen in steel

[P52] A. Markström, Y. Du, S.H. Liu, L.J. Zhang, L. Kjellqvist, J. Bratberg, A. Engström TCAL1: A new thermodynamic database for Aluminium alloys

[P53] C.P. Wang, S.X. Gan, X.J. Liu A thermodynamic database of phase diagram in alloy systems including rare earth elements

[P54] Nara M. Guimarães, Danieli A. P. Reis, Carlos de Moura Neto, Gilberto C. Coelho, Daniel S. de Almeida Thermodynamic Modeling of the Y2O3-Nb2O5 System

114


[P55] Weiping Gong, Yue Wu, Marcelle Gaune-Escard Thermodynamic assessment of CsBr-LnBr3 system (Ln = La, Ce, Tb)

Diffusion and phase transformation modeling

[P56] Carolina Corvalan, Manuel Iribarren, Julio Sola Calculation of different Co diffusion kinetics along alpha-Zr grain boundaries at power reactor temperatures

under normal conditions

[P57] K. C. Hari Kumar, V. B. Rajkumar, B. S. Srinivas Prasad Numerical simulation of precipitate evolution in ferritic-martensitic power plant steels

[P58] M. Kajihara, K. Motojima, T. Asano Microstructure Evolution by Solid-state Reactive Diffusion in the (Ni−Cr)/Sn System

[P59] Marcos Flavio de Campos, Jose Adilson de Castro, Sergio Antonio Romero, Marcelo F Moreira, Fernando J. G. Landgraf

Phase Transformations In The Annealing Of Sm-Co-Fe-Cu-Zr Magnets

[P60] S. Sankaran, N. Maheswari, V. B. Rajkumar, S. G. Chowdhary, K. C. Hari Kumar Kinetic Simulation of Carbon migration During Quenching and Partitioning (Q and P) Treatment of Steels

Experimental measurements

[P61] Annie Antoni-Zdziobek, Sabine Lay, Coraline Crozet Experimental determination of phase equilibria in the iron-rich side of the Cu-Fe-Ni system between

873 K and 1273 K

[P62] Carlos Angelo Nunes, Gilberto Carvalho Coelho,Belmira Benedita de Lima, Tales Ferreira Villela, Nicolas David, Jean Marc Fiorani, Michel Vilasi

Experimental Investigation and Thermodynamic Assessment of the V-Si-B System

[P63] C. Vébert, Y. Hamini, L. Héricher, S. Michon, L. Aranda, P. Berthod Casting and characterization of Ni-, Fe(Ni)- and Fe-based 30%Cr-containing alloys strengthened by TaC;

comparison with thermodynamic calculations

[P64] Changjun Wu, Xuping Su, Jianhua Wang, Ya Liu, Haoping Peng, Hao Tu Experimental investigation and thermodynamic modeling of the Zn-V-X (X=Sn, Ti, Si) ternary systems

[P65] D. Kobertz and M. Müller Experimental Studies and Re-assessment of the Quasi-binary Systems containing the Sulfates of Sodium,

Potassium, and Calcium by Differential Thermal Analysis and X-Ray Diffraction

[P66] Herbert Ipser, Rajesh Ganesan Thermochemical Study of Rare Earth-Cadmium Systems: the System Gd-Cd

[P67] Hongxiao Li, Y.P. Ren, N.N. Zhao, M. Jiang, G.W. Qin, S.M. Hao Experimental investigation on the ternary compound and γ-Ni solvus in the Ni-rich corner of the

Nb-Ni-Ti system

[P68] Janusz Pstrus, Tomasz Gancarz, Przemyslaw Fima Design of new lead-free solders on the example of Sn-Zn-In

[P69] K.C. Hari Kumar, S. Balakrishnan, K. Anathasivan, S. Anthonysamy, V. Ganesan, P.R. Vasudeva Rao Solidus and liquidus measurements in the U-Zr binary system

[P70] Kazuya Shinagawa, Toshihiro Omori, Katsunari Oikawa, Ikuo Ohnuma, Kiyohito Ishida, Ryosuke Kainuma Experimental Determination and Thermodynamic Analysis of Phase Equilibria in the Ni-W and

Ni-Al-W systems

115


[P71] Khurram Yaqoob, Jean-Marc Joubert Experimental determination of isothermal sections of Mo-Ni-Re system at 1200°C and at 1600°C

[P72] Leandro Nakamura Alves Vieira, Marco Antonio da Cunha, Fabricio Luiz de Alcantara, Ronaldo Antônio Neves Marques Barbosa

Microstructural aspects and computational thermodynamics of secondary phase precipitation in Fe-Si 3%wt. steel

[P73] Ligang Zhang, Patrick J. Masset, Libin Liu Thermodynamic analysis of the Al-Cu-Er ternary system

[P74] Mirsalim M. Asadov Physicochemical and thermodynamic properties of the GeSe2 -А2В6 (А2 = Hg; Cd; В6 = S, Te) systems

[P75] Mohammad Mezbahul-Islam, Mamoun Medraj New intermetallic compounds in the Mg-Ni-Y system

[P76] Pavel Broz, Georgui Vassilev, Vanya Gandova, Jiri Bursik Study of Phase Transformations and Phase Equilibria in the Ni-Sn-Zn System

[P77] Przemyslaw Fima, Janusz Pstrus, Tomasz Gancarz Thermodynamic and thermophysical properties of Sn-Zn-In alloys

[P78] Rogério Navarro Correia de Siqueira, Roberto Ribeiro de Avillez, Angelo Márcio de Souza Gomes, Eduardo Granado Monteiro da Silva

Heat capacity at low temperatures and molar entropy of stoichiometric Al2MnO4

[P79] S. Shimenouchi, I. Ohnuma, T. Omori, R. Kainuma and K. Ishida Experimental Investigation of Phase Equilibria at Low Temperatures (< 600 °C) in the Fe-Ni Binary System

[P80] Takashi Miyamoto, Ikuo Ohnuma, Kiyohito Ishida, Ryosuke Kainuma Combinatorial technique for phase equilibria determination of Pt-Fe-X (X=Al, In) sytems

[P81] Tales Ferreira Villela, Vanessa Motta Chad, Flávio Ferreira, Gilberto Carvalho Coelho, Carlos Angelo Nunes, Nicolas David, Jean-Marc Fiorani, Michel Vilasi

Thermodynamic Modeling of the Cr-Si-B System and Experimental Evaluation of Critical Points in the Cr-rich Region

[P82] Tomasz Gancarz, Przemyslaw Fima, Janusz Pstrus Thermodynamic and physicochemical properties of Zn-Al-In alloys

[P83] Y. Yu, C.P. Wang, X.J. Liu, R. Kainuma, K. Ishida Experimental confirmation and thermodynamic analysis of existence of fcc-type miscibility gap at high

temperatures in some Cu-Ni base alloy systems

[P84] Dębski A., Gąsior W., Moser Z., Major Ł., Major R. Formation enthalpy of the BLi and B3Li intermetallic compounds by solution calorimetric method

[P85] Gasior W., W. Zakulshi, A. Debski Phase Relations in the Ca-Li System

First principle calculations

[P86] Cláudio Geraldo Schon, Raymundo Arróyave On the cluster expansion method

[P87] Críspulo E. Deluque Toro, Susana Ramos de Debiaggi, Gabriela F. Cabeza, Armando Fernández Guillermet Ab initio study of thermodynamic, structural and electronic properties of stable and metastable compounds in

the Me-X systems (Me = Cu, Ni; X = In, Sn)

116


[P88] Fritz Kormann, Alexey Dick, Tilmann Hickel, Jörg Neugebauer Integrating finite temperature magnetism into ab initio free energy calculations

[P89] Hanchul Kim, Ji-Young Noh Ab initio Calculations on the Effect of Mn Substitution in Fe3AlC

[P90] Ilya Polishuk Hybridizing SAFT and cubic EOS: what can be achieved?

[P91] Cláudio Geraldo Schon, Pablo Guillermo Gonzales-Ormeño, Ney Sodré, Helena Maria Petrilli Ab-initio calculation of the BCC Fe-M (M = Ti, V, Cr, Zr, Nb, Mo): new results on a correlation between

compound stability and magnetism

[P92] Pablo Guillermo Gonzales-Ormeño, Ney Sodré, Helena Maria Petrilli, Claudio Geraldo Schon Ab-initio calculation of the metastable bcc Al-M (M = Sc, Ti, V, Cr, Y, Zr, Nb, Mo) phase diagrams

[P93] R. Taniguchi, S. R. Nishitani, Y. Ohno, and I. Yonenaga First principles calculations of the copper silicide precipitates

[P94] Vadym Kulish, Man-Fai Ng, Zhong Chen, Ping Wu First-principles Study on Si Clusters Supported on Carbon Nanotubes (CNTs) and Graphene

[P95] W.Y. Wang, H.Z. Fang, S.L. Shang, Y. Wang, Z.K. Liu, Suveen Mathaudhu Predicting grain boundary structures and properties from ab initio molecular dynamics and first-principles

calculations

[P96] Masaki, M. Sugimoto, Y. Yamamoto, Y. Miyamoto and S. R. Nishitani First principles calculations of 18R Mg alloys

[P97] Yosuke Yamamoto, S.R.Nishitani, and T.Kaneko First principles calculations on vibration free energies of SiC polytypes

[P98] Oleksandr Malyi, Zhong Chen, Ping Wu Effects of sulfur and nitrogen impurities on the properties of the solid oxide fuel cell anode materials

Modeling and fundamental aspects

[P99] Hannu Sippola Critical evaluation of the sulfuric acid - water system in wide concentration and temperature range

[P100] Jolanta Romanowska Predicting thermodynamic properties of ternary systems by means of finding a function value inside a

Gibbs triangle

Nanomaterials

[P101] Adela Zemanova, Jiri Bursik, Jiri Sopousek, Jan Vrestal, Pavel Broz Calculation of Ag-Sn Phase Diagram Including the Size Effect

[P102] Jan Vřesťál, Jiří Pinkas, Jiří Sopousek, Pavel Broz, Jří Bursík Calculation of nanoalloys phase diagrams

117


Abstracts: Poster Presentations

Applications to process and materials design and development

118


[P1]Design of a Ductility-Dip Cracking Resistant Ni-Cr-Fe Alloy

Antonio J. Ramirez, Jimy Unfried S.

Brazilian Synchrotron Light Laboratory

Engineering of precipitates size, morphology and distribution, grain boundaries morphology and solute partitioning within FCC matrix can be an effective method to improve the resistance of Ni-Cr-Fe alloys to the high temperature fracture phenomena known as ductility-dip cracking (DDC). DDC is a solid state intergranular fracture phenomenon associated with welding and high temperature forming that plagues several FCC materials, including the solid solution strengthened Ni-base alloys, Cu-base alloys, and stainless steels [1]. This phenomenon is characterized by a severe ductility reduction within homologous temperature range between 0.4 and 0.8. Several works have reported that the high temperature grain boundary sliding is the fundamental mechanism that governs DDC for alloy 690 [2]. Calphad methodology was applied in this work to perform both thermodynamic and kinetic modeling of the alloy 690 including few chemical composition modifications in order to optimize the DDC resistance without compromising other properties [3]. Primary carbonitrides precipitation and solidification have been evaluated for as-welded Ni-base alloy 690 modified with Nb, Mo, and Hf additions. Actual as-welded samples were produced and characterized using electron microscopy (SEM, TEM, and EBSD). The DDC resistance was evaluated using a dedicated SEM-in situ thermo-mechanical setup. The additions of Nb (<2.5%-wt) and Hf (<0.4%-wt) increased the mass fraction and the primary carbonitrides precipitation temperature. Consequently, the material presented a delayed grain boundary migration and the grain boundaries morphology changed from flat to undulated for the as-welded condition. The occurrence of wavy grain boundaries and the Mo atoms distribution (<4.0%-wt) in gamma matrix could be related to the grain boundary sliding blocking and to the dislocation movement restriction at high temperatures, which has been shown to improve DDC resistance in the redesigned 690 alloy.

Key words: Ni-based alloys, kinetic modeling, welding, ductility dip cracking.

[1] Ramirez, A. J.; Garzón, C. M. Hot cracking phenomena in welds II, 427-454, 2008. [2] Ramirez, A.J.; Lippold, J.C. Hot Cracking Phenomena in Welds, 19-41, 2005. [3] Unfried S, J.; Torres, E.A.; Ramirez, A.J. Hot Cracking Phenomena in welds III, in press, 2011.

119


[P2]Effect of surface energy on the zirconia-yttria phase diagram:

a CALPHAD approach

Ashutosh S. Gandhi, Abhiram Muralidhar, K.C. Hari Kumar

Indian Institute of Technology Madras, Dept. Met.& Mater. Engg., Chennai 600036, India

Yttria stabilised zirconia ceramics (YSZ) are widely used for their attractive properties such as transformation toughening, high ionic conductivity, low thermal conductivity and high thermal expansion coefficient. The useful phases and microstructures of zirconia are almost always metastable. Zirconia phase stability is influenced by surface/interfacial energies of the phases [1]. Stresses also influence phase stability. In this work we have modified Gibbs energy functions of a few phases of ZrO2-YO1.5 system by adding surface energy contributions [2]. The phases selected are monoclinic (m), tetragonal (t) and cubic (c). Phase boundaries and important T0 lines have been calculated for particle sizes down to 20 nm. The results are correlated with the observed phase stability reported in the literature. For instance, transformation toughening requires presence of a tetragonal phase with Ms temperature just below room temperature. This leads to stress-induced martensitic transformation in the crack wake during fracture with enhanced fracture toughness. The Ms temperature is related to the T0(t/m). It is known that pure t-zirconia can form at room temperature if the surface area is sufficiently large e.g. in nanoparticles. The t-YSZ can be stabilised if the surface area is large or stresses are present. Also, aging of non-transformable t’ in thermal barrier coatings and c-YSZ in fuel cells are important issues. Implications of our results for these scenarios will be discussed.

Key words: zirconia, surface energy, nanoparticles.

[1] M.W. Pitcher, S.V. Ushakov, A. Navrotsky, B.F. Woodfield, G. Li, J. Boerio-Goates, B.M. Tissue, J. Am. Ceram. Soc., 88, 160, 2005. [2] M.J. Mayo, A. Suresh, W.D. Porter, Rev. Adv. Mater. Sci., 5, 100, 2003.

120


[P3]Evaluation of the Chemical Composition of Irradiated Mixed Carbide Fuel

Jean-Christophe Dumas, Jean-Paul Piron, Chantal Martial

Commissariat à l’Energie Atomique, DEN/DEC/SESC - CEA Cadarache - 13108 Saint-Paul Lez Durance Cedex, France

The mixed carbide (U,Pu)C is a reference material for Generation IV (Gas-cooled Fast Reactor or Sodium Fast Reactor) nuclear fuels. The creation of fission products (FP) can modify the physical and chemical properties of the fuel behaviour during irradiation. As they control the carbon activity in the fuel, it is important to assess the influence of burn-up and temperature on the speciation of FP (solid, liquid and gaseous phases). The first part of this study is dedicated to the thermodynamic modelling of the irradiated fuel introduced into the FactSage code. The second part deals with the evaluation of the chemical state of the fission products as a function of burn-up and initial composition (carbon content) for representative operating temperature values. For that purpose, we have used the isotopic composition data given in [1] and compared our results to those obtained with the Solgasmix-PV computer program code and also to experimental observations on irradiated fuels from [2]. Special attention is paid to the evolution of the carbon over metal (C/M) content with burn-up. Indeed, as the C/M ratio decreases with burn-up, the initial M2C3 phase present in the fuel might disappear as soon as C/M decreases below one and due to the narrow non-stoichiometry of the MC phase [3,4], a liquid (U,Pu) phase might appear, which is not recommended for safety criteria. Finally, comparison of our results obtained on of un-irradiated (U,Pu)C fuel (isothermal ternary sections, carbon and plutonium activities) with those calculated by the TCC Software using the CALPHAD description of the (U-Pu-C) system developed in the frame of the FuelBase Project [5] shows significant differences. Those last results lead us to conclude that a complete CALPHAD description of the whole (U-Pu-C-FP) system would be helpful if we want to improve the operating conditions of this kind of fuel.

Key words: Nuclear Fuels, Mixed Carbide, Fission Products, Chemical Composition, FactSage, Thermo-Calc, FuelBase Project.

[1] R. Agarwal, V. Venugopal, J. Nucl. Mater. 359, 122 (2006). [2] Hj. Matzke, Science of Advanced LMFBR Fuels, Elsevier Science Publishers B.V. (1986). [3] H. Kleykamp, J. Nucl. Mater. 221, 131 (1985). [4] H. Holleck, Thermodynamics of Nuclear Materials, IAEA Vie.

121


[P4]Effect of Boron on the Microstructure and Mechanical Properties of

Cold Rolled Multiphase Steels

Fábio Dian Murari1, André Luiz Vasconcellos da Costa e Silva2, Roberto Ribeiro de Avillez3

1Usiminas 2EEIMVR-UFF

3PUC - RIO

The influence of boron content on the phase transformation characteristics, microstructure and mechanical properties of multiphase steels was investigated by means of computational thermodynamics (Thermo-Calc), dilatometry, quantitative metallography and tensile tests. The steels were prepared as 50 kg ingots in an induction furnace operating under argon gas atmosphere with boron contents in the range of 0 to 47 ppm. The ingots were cut into blocks of 35 mm thick, which were reheated to 1250°C for 1 h and hot rolled in six passes to 7.0 mm thick. The hot rolled sheets were machined and then cold rolled to a final thickness of 1.2 mm. The continuous annealing cycles were carried out in a Bähr dilatomer and in a Gleeble machine. It was found that the boron did not influence the amount of austenite formed during the heating and soaking steps in the continuous annealing simulations. However, the boron influenced the austenite transformation during the cooling step, reducing the amount of ferrite and increasing the amount of bainite. Regarding mechanical properties, the boron addition increased the mechanical resistance and reduced the ductility. The steels containing boron levels of up to 27 ppm exhibited the largest effect. The results of amount of austenite achieved by means of the Thermo-Calc presented themselves overestimated compared to those obtained by dilatometry and metalography, especially for soaking temperatures below 800°C.

Key words: Multiphase steels; Boron; Thermo-Calc; Dilatometry.

[1] Llewellyn, D. T. Ironmaking and Steelmaking, Vol. 20, Nº 5, 1993, p. 338 - 343. [2] Pressouyre, G. M.; Primon, G.; Blondeau, R. International Conference on HSLA Steels’85, 1985, p. 335-350. [3] Bhadeshia, H. K. D. H.; Svensson, L. E. Model for Boron Effects in Steels Welds. International Conference on Modelling and Control of Joining Processes, Orlando, Florida (1993), ed T. Zacharia, American Welding Society, p. 153-160.

122


[P5]The role of atmosphere on the interfacial interactions between molten oxide

glasses and silicon carbide

Fiquiri Hodaj1, O. Mailliart2, V. Chaumat2

1Grenoble Institute of Technology 2CEA Grenoble

A method for joining silicon carbide between 1300°C and 1600°C under air using calcium aluminosilicate glasses has been developed [1]. This technology avoids protective atmosphere resulting in high production cost and allows repairing more easily damaged joined components. Many studies have been performed on the joining of SiC using glass-ceramics under vacuum or in neutral gases. Only a few studies are available in the literature on interfacial interactions between molten glasses and SiC as well as on the joining of SiC by glass-ceramics under air. In this work interfacial interactions between calcium aluminosilicate glasses and SiC under air are studied by performing wetting and joining experiments on polycrystalline SiC between 1100°C and 1600°C. Some specific experiments are also performed: (i) on silica or monocrystalline SiC under air and (ii) on polycrystalline SiC under argon or vacuum. The interfacial interactions between glass and SiC strongly depend on the temperature, the furnace atmosphere and the content of silica glass. Moreover, under air, there is an enormous difference between the reactivity in a sessile drop configuration and in a brazing configuration. The purpose of this presentation is to focus on fundamental issues of interfacial interactions on the molten oxide glasses SiC system. The confrontation of results of thermodynamic calculations with experimental observations allowed to elucidate the role of oxygen on these interfacial interactions.

Key words: Interfacial interactions; wetting; SiC; molten glasses; thermodynamic calculations; diffusion.

[1] Mailliart, O. Chaumat, V. Hodaj, F. French Patent Application N° 08 55857 filed on September, 1, 2008.

123


[P6]Title Improve cleanliness of SAE 1045 Al-killed steel grade with applied in

the automobilistic industry, using computational thermodynamic

Humberto Luiz Gama de Magalhães1, Carlos Antônio da Silva2, Andre Luiz Vasconcelos da Costa e Silva3

1Arcelormittal Monlevade 2Redemat / Universidade Federal de Ouro Preto - UFOP

3Universidade Federal Fluminense *e-mail: [email protected]

Steelmaking have been devoting large amount of resources to improve processes and products in order to face a strong competition based on quality requirements. Inclusion Engineering has been included in the steelmaking vocabulary as a means of forecasting the type of inclusion, its morphology, size and distribution in the steel as well as its thermo-mechanical behavior. One of the several inclusion engineering tools is computational thermodynamics. Its application allows the inclusion chemistry to be foreseen as a function of steel composition, pressure and temperature. In this work Thermo-Calc® and CEQCSI software have been used to evaluate the possibility of formation of various types of inclusion. It has been also investigated the concept of “casting window” and the formation of macroinclusions (complex inclusions). The experiment included some statistic tools employed with the main objective of measuring the impact of variables: size, distribution, morphology and area in percentage of the CaS and oxisulfides inclusions where the occurrence of macroinclusion is minimized. The identification of the inclusions was made through SEM-EDS. Box-plot diagrams suggest that the best configuration to achieve a criterion based on reducing size variability of type 3 oxisulfide and calcium sulfide. Main effect diagrams shows the trend to higher calcium sulfide content for increasing CaSi addition and sulfur content. The manganese sulfide content increases for increasing CaSi addition.

Keywords: Computational thermodynamics; inclusion engineering; Thermo-Calc®; CEQCSI; SAE1045; macroinclusion.

[1] Costa e Silva, A.. Equilibrium calculation at steel shop by computational thermodynamics. Tecnologia em Metalurgia e Materiais, São Paulo, v.03, no.01, pág. 45-52, jul.-set., 2006. [2] Kirsch-Racine, A., Bomont-Arzur, A., Calcium treatment of medium carbon steel grade for machinability enhancement: from the theory to industrial practice. Revue de Métallurgie-CIT, n.12, p.591-597, 2007.

124


[P7]Computational Thermodynamics and Spheroidisation of Bearing Steels

In Gee Kim, Jee Yong Lee

POSTECH (Pohang University of Science and Technology), Republic of Korea

Bearings are vital components of almost all machines. Steels supplied to the bearing manufacturer for making raceways are in the form of tubes or forgings, whereas the rolling elements are made by cold forging drawn wire. The aim of spheroidise annealing is to facilitate machining and cold-forming operations by inducing a microstructure which is a mixture of relatively coarse cementite particles and ferrite; the roughness of machined surfaces is also reduced in the process. Reasonably large cementite particles and a small number density is conducive to less wear on the tools used for machining. Lamellar carbides of the type associated with incomplete spheroidisation lead to enhanced tool-degradation. Spheroidisation reduces the hardness of the steel supplied to a bearing manufacturer to about 230 HV. There are many properties required from bearing steels. This study is in its first stage limited to exploring modifications which enhance the rate of spheroidisation, with a focus on the ACM temperature. Beginning with a typical bearing steel as the base, Fe-1C-1.45Cr-0.25Si-0.35Mn, having about 910 °C of ACM temperature, attempts were made to increase the ACM temperature and the fraction of cementite present at the ACM temperature. Using the ThermocalcTM with the TCFE6 database, we build up a software package to generate phase diagrams affected by all the possible elements from the database systematically. It is found that B, P, S and Cr are effective to increase ACM. We found that the effect of boron seems abnormal, which suggest to refine thermodynamic data of boron. Interestingly, the broadening of eutectoid reaction region was observed for phosphorus and sulfur cases, but a further study should be required by allowing the P and S compound phases. The volume fraction of cementite around the ACM temperature of each composition was made, and it is concluded that P and Cr are effective in providing large volume fraction with high ACM temperature.

Key words: spheroidisation, cementite, martensite, alloy design.

125


[P8]Thermodynamic Simulation Of Nitrogen And Manganese Contents

In Delta Ferrite Formation Of Plastic Mold Stainless Steel

José Britti Bacalhau, Eduardo Netto de Souza, Alexandre Bellegard Farina, Celso Antonio Barbosa

Villares Metals SA

Some grades of low carbon and low nickel martensitic stainless steels are applied in components of plastic injection molds like hot runners and refrigeration plates because of their corrosion resistance. The production of these steels has special controls due the low temperature range in forging or rolling. If the deformation temperature is too high, there is the precipitation of delta ferrite in steel microstructure, which damages the material corrosion resistance. In the case of low temperature it is required excessive power of the forging press or rolling mill. The present work discusses the use of thermodynamic simulations to develop a new stainless steel with higher deformation temperature range. The effect of Nitrogen and Manganese contents in delta ferrite formation has been modeled in the thermocalc software with TCFE6 thermodynamic database. The results obtained by computer modeling it were evaluated in alloys produced in pilot scale in a VIM furnace. Samples of these materials were heated to different temperatures and by metallographic analysis the amount of delta ferrite precipitated was measured. The accuracy of results between modeling and laboratory investigation were extremely high. A good combination of chemical composition, mainly N and Mn contents, enabled a steel development with deformation temperature range of 40 to 90 °C higher than others commercial such grade steels.

Key words: Thermodynamic Simulation; Delta Ferite; Stainless Steel; Plastic Mold.

[1] Roberts, George, Krauss, George, Kennedy, Richards. Tool Steel. 5. ed. ASM International, 1998. [2] Hillert, M. The Compound Energy Formalism. Journal of Alloys and Compounds 320 (2001), p. 161-176. Elsevier. [3] Roberts, George, Krauss, George, Kennedy, Richards. Tool Steel. 5. ed. ASM International, 1998. [4] ASM Handbook, Properties and Selection: Stainless Steels, Tool Materials and Special-purpose Metals, 9th ed., volume 3.

126


[P9]Microstructural Evolution in the Aging of Inconel 718

Marcos Flavio de Campos1, Shimeni Baptista Ribeiro1, Jefferson Fabricio Cardoso Lins1, Alexandre Bellegard Farina2

1Universidade Federal Fluminense 2Villares Metals S/A

In the case of superalloys, formation of precipitates in grain boundaries is deleterious for the creep properties. Thus, CALPHAD method is an important aid to predict superalloys compositions able to resist longer periods at high temperatures. It should be reminded that each INCONEL 718 has slightly different chemical composition. It is relevant to note that minor alloying elements may change the amount of volumetric fraction of the phases and also the precipitation sequence. The main hardening mechanism of .Inconel 718 is due to the formation of a semicoherent precipitate gamma double prime (Ni3Nb) (body centered tetragonal) and, in a lesser extent, the coherent precipitate gamma prime Ni3(Al,Ti) (fcc L12 structure) also contributes for the mechanical properties. However, with increasing aging time, coherent gamma double prime (Ni3Nb) tends to transform in Ni3Nb -delta [orthorhombic, DO22 structure]. This delta phase usually precipitates at grain boundaries. In the present study, the precipitation hardening in Inconel 718 alloys was studied in detail, using techniques for microstructural characterization, as SEM-EBSD (Scanning Electron Microscope with Electron Backscatered Diffraction) and X-ray Diffraction (XRD) Synchrotron with Rietveld Analysis. The studied Inconel 718 alloy was submitted to solubilization at 980 °C during 30 min under vacuum, followed by a quenching in water. The samples were subsequently submitted to annealing at the temperature of 680 °C during 1h, 2h, 4h, 8h, 10h, 20h, 50h and 100 h. Carbides as MC were identified in the microstructure. After 10h of heat treatment, delta phase can be identified along grain boundaries. These results are in agreement with ThermoCalc calculations (database TCNI8), which predicted the presence of delta phase at lower temperatures than that suggested in some previous studies [1].

Acknowledgements FAPERJ CNPq LNLS, Research Project D10B - XPD-9924.

Key words: Inconel 718, EBSD, Synchrotron XRD , precipitates.

[1] C. T. Sims, N. S. Stoloff and W. C. Hagel, Superalloys II (published by John Wiley & Sons, New York). 2nd Ed., Wiley - Interscience, 1987.

127


[P10]Evaluating segregation in HSLA steels using computational thermodynamics

Meire Guimarães Lage1, André Luiz V. da Costa e Silva2

1USIMINAS 2Universidade Federal Fluminense

The level of segregation in steel plates used to manufacture large diameter high strength pipe is important to pipe manufacture and performance. In this work, as part of the alloy design process, the level of segregation of different HSLA steel compositions was evaluated using computational thermodynamics. Equilibrium and Scheil-Gulliver model calculations were used to identify the most promising compositions. Phase diagrams, phase fraction diagrams and the progress of the composition of the various phases as a function of temperature were evaluated, to quantify the segregation towards the end of solidification. Results indicate that S is the stronger segregating element, as expected, but also that Nb, C and P segregate considerably. P and Mn segregation are well known to be associated with banding in these products and the present results confirm this. The enrichment of the liquid phase in S, P and Nb is related not only to the content of these elements but also to the steel C content. Even using only these two extreme models - equilibrium and Scheil - the results are useful to support the alloy design, in special concerning the evaluation of segregation of C, Mn, S, P, Nb e Ti, elements that have a significant influence both on mechanical properties and on the resistance to hydrogen embrittlement of the steels used for large diameter piping. In the next step, these results will be compared with the results of the continuous cast and controlled rolled plates.

Key words: Computational thermodynamics; segregation; HSLA steels.

[1] Chakrabarti, D. et al. Metallurgical and Material Transactions A, Vol. 39A, p. 1963-1977, Aug. 2008. [2] Mondragón, J. J. R. et al. ISIJ International, Vol.48, No.4, 2008, p.454-460. [3] Schneider, A. et al. International Journal of Materials Research, No. 6, 2008, p. 674-679.

128


[P11]Experimental and thermodynamic study of ternary Fe-30Cr-xC

carbon-rich alloys with x varying from 2.5 to 5.0wt.%

M. Ba,1 A. Dia,1 P. Berthod, L. Aranda,2 Th. Schweitzer,2 P. Villeger2

1University Henri Poincaré, Faculty of Sciences and Technologies 2Institut Jean Lamour, University Henri Poincaré, Faculty of Sciences and Technologies

White cast irons are not expensive very hard alloys which can be used for wear resistance. Other iron alloys candidates for the same applications, and offering a better resistance against high temperature oxidation or corrosion, as well as a higher refractoriness, are Fe-based chromium –rich alloys also containing a great quantity of carbon. The aim of this work is to explore the microstructures and of the melting temperature ranges of alloys belonging to the ternary family Fe(bal.) - 30Cr-xC (in wt.%), with x increasing from 2.5 to 5%, and to compare these metallographic data with thermodynamic calculations results. Six alloys were synthesized by foundry practice and they were metallographically characterized in their as-cast state as well as in their heat-treated states (50 h at 1000, 1100 and 1200 °C). This was done by using Scanning Electron Microscopy, measuring their carbides surface fractions. Additionally DTA/DSC experiments were carried out to assess the melting-start and melting-end temperatures of the alloys. The characterization of both matrix and carbides was completed by performing X-Ray Diffraction. Natures and fractions of the different phases, as well as the solidus and liquidus temperatures, were compared to results issued from Thermo-Calc calculations. For a carbon content equal to 2.5wt.% the alloy microstructure is hypo-eutectic with presence of dendrites of Fe matrix delimiting the {Fe matrix + chromium carbides}- eutectic spaces, while for carbon contents equal to 3wt.% and higher dendrites are replaced by coarse pro-eutectic carbides. Contrarily to what can be observed for similar alloys based on nickel or cobalt lamellar graphite never appeared in these iron alloys for the same carbon contents. Matrix is Back Centered Cubic, and carbides are exclusively Cr7C3 for all the as-cast alloys.

Key words: Iron Alloys; Very High Carbon; Chromium Carbides; Phase Fractions; Melting Range; Thermodynamic Calculations.

[1] P. Berthod, E. Souaillat, O. Hestin, As-cast microstructures of {M-30Cr-0 to 5%C} ternary alloys. Part 1: Nickel-Base alloys, Materials Science: An Indian Journal 2010, 6(4), 260- 266. [2] P. Berthod, O. Hestin, E. Souaillat, As-cast microstructures of {M-30Cr-0 to 5%C} ternary alloys. Part 2: Cobalt-Base alloys, Materials Science: An Indian Journal 2010, 7(1).

129


[P12]Thermodynamic calculations used for characterizing the sub-surfaces changes

induced by high temperature oxidation for carbides-reinforced alloys

Patrice Berthod

Institut Jean Lamour, University Henri Poincaré, Faculty of Sciences and Technologies

In addition to the external oxide scale, oxidation at high temperature (typically 1000°C) induces sub-surface modifications as depletion in Cr or Al, formation of internal oxides and other phenomena depending on the alloy. In the specific case of superalloys or other refractory alloys strengthened by carbides, frequent phenomena are the disappearance of carbides over a depth increasing with time and/or, in some cases, the precipitation of new carbides along an internal alloy band separating the outer carbide-free zone and the not modified bulk. It can be useful to characterize this whole zone affected by oxidation to complete the knowledge of its new chemical composition by determining the new carbon content. Image analysis and thermodynamic calculations allow specifying this characteristic, and furthermore the new level of local refractoriness. Different refractory alloys - cobalt-based, nickel-based or iron-based - containing different types of interdendritic carbides (Cr7C3, TaC, ...) were elaborated by foundry and subjected to oxidation at different high temperatures (1000 to 1300°C). The oxidized samples were metallographically prepared and their sub-surface microstructures examined by Scanning Electrons Microscopy. The depths of the formed carbide-free zones were measured, the new carbides were identified by microprobe/WDS measurements and image analysis was performed to measure their surface fractions. Thermodynamic calculations using Thermo-Calc were performed first to assess the new carbon distribution, and second for the estimation of the new solidus temperatures displayed by the outer zone of alloy. It appears that the C content is now extremely low in the carbide-free zone, leading to a higher local refractoriness which can eventually protect the {partially melted}-bulk alloy from catastrophic oxidation in case of sudden temperature increase. After oxidation at 1000°C new carbides precipitated in a band between the carbides-free zone and the bulk.

Key words: High Temperature Oxidation; Carbides-reinforced Alloys; Thermodynamic calculations; Carbon Distribution; Sub-surface Refractoriness.

[1] D.J. Young, High Temperature Oxidation and Corrosion of Metals, Elsevier, Amsterdam, 2008. [2] P. Berthod, Experimental and thermodynamic study of nickel-based alloys containing chromium carbides. Part II: Study of the sub-surface characteristics of Ni-30wt%Cr-xC alloys oxidized.

130


[P13]The effect of Cr and Mo in the formation of intermetallic phases

Rodrigo Freitas Guimarães1, Hélio Cordeira de Miranda2, Hamilton Ferreira Gomes de Abreu2, Fernando Henrique Costa Sabóia1

1IFCE 2UFC

Molybdenum (Mo) containing stainless steels are commonly used to prevent naphthenic acid corrosion (NAC) in the refining industry. The development of new alloys with high content of Mo associated with Cr or with Cr and Ni is one of the strategies to reduce the effects of naphthenic acid corrosion. In this work 100 kg ingots of novel alloys with Cr of 9, 15 an 17 wt% and Mo 5, 7 and 9 wt % were cast, forged and hot rolled. Prior to the manufacturing stage a study of phases and intermetallic precipitates was done using Thermocalc. Phase diagrams for different chromium and molybdenum contents were plotted to identify and calculate phases formed at different temperatures. To validate the results obtained in the simulation, microstructural characterization was performed by scanning electron microscope (SEM), electron back scattered diffraction (EBSD) and energy-dispersive X-ray spectroscopy (EDX). The addition of chromium and molybdenum favors a ferritic microstructure of the alloys studied as well as the formation of intermetallic phase as chi, sigma, mu and carbides M6C and M23C6. The analysis of phases by SEM and EDX confirmed the formation of the ferritic phase and carbides M6C and M23C6. The content of elements present in the carbides formed were influenced by the content of chromium and molybdenum present in each experimental alloy. The intermetallic phases chi, sigma, mu were well identified by EBSD. The results indicated that the use of thermodynamic software is a good tool to foresee possible problems in the development of Fe-Cr-Mo alloys.

Key words: Molybdenum, Chormium and Internmetallic Phases.

[1] ASM HANDBOOK - Casting, “Nickel and Nickel Alloys”, Vol. 15, 10th Edition, ASM Metals Park, Ohio 1993b. [2] ASM HANDBOOK - Welding, Brazing and Soldering, “Selection of Nickel, Nickel-Cooper, Nickel-Chromium, and Nickel-Chromium-Iron Alloys”, Vol. 6, 10th Edition, ASM Metals Park, Ohio.

131


[P14]Chlorination of vanadium oxide under the presence of graphite

Rogério Navarro Correia de Siqueira, Roberto Ribeiro de Avillez, Eduardo de Albuquerque Brocchi

PUC-Rio

Chlorination is an important process for extracting metals of high economic value from minerals and industrial wastes, in particular, if volatile chlorides and or oxychlorides are produced, which in a further step can be separated through selective condensation. Graphite has proven to be an important reducing agent to chlorination, as it reacts with oxygen, promoting the process driving force. The present work focuses on the chlorination of vanadium oxide under the presence of graphite. Thermodynamic data for the vanadium chlorides and oxychlorides are reviewed and compared with the available database. The equilibrium thermodynamic conditions for the vanadium oxide chlorination are calculated for different gas atmospheres with and without graphite as a reducing agent. The atmosphere composition and the reaction temperatures are determined from predominance diagrams.

Key words: clorination, vanadium pentoxide, graphite, vanadium chloride, vanadium oxychloride.

132


[P15]Prediction of liquid phase behavior during the rapid transient liquid phase

bonding process of steel using cementite filler metals

Takashi Maehsima, Kouji Tanaka, Tadashi Ohshima and Hisaaki Takao

Toyota Central R&D Labs., Inc. Nagakute, Aichi 480-1192, JAPAN

A plane-to-plane bonding by the surface liquid reaction from an inserted foil enables a simplified forming of hollow or complex steel parts. We have proposed a rapid transient-liquid-phase (TLP) bonding process of steel using monophase cementite (θ) foils which was intentionally-created by substituting chromium for a part of iron1). The θ filler metal is suitable as inserted foils because the emerged liquid layer ensures the dissolution of alloying elements from base steel with melting its surface, followed by quick isothermal solidification owing to the rapid carbon diffusion. In this study, the effect of heating rates on the eutectic liquid behavior during TLP bonding process was investigated using a multicomponent diffusion simulation. One-dimensional half model as illustrated schematically in figure 1 is considered due to the inherent symmetry of the bond. The simulation showed that the maximum thickness of liquid layer increased with an increasing heating rate (figure 2). The maximum liquid thickness can be estimated by residual thickness of the θ foil just before emergence of the liquid during heating. The result is interpreted as heating rates affect the degree of solid dissolution of θ foils resulting in determination of the maximum liquid thickness.

Key words: transient-liquid-phase bonding, diffusion simulation, eutectic liquid, heating rate, cementite, dissolution.

Fig. 1 Geometry model for multicomponent diffusion simulation between base metal and θ foil.

Fig. 2 Changes in maximum liquid thickness with the heating rates.

[1] K.Tanaka, H.Takamiya, N.Iwata and K.Nakanishi: Tetsu-to-Hagane, Vol.96 (2010) No.6.

133


[P16]“Wrong and Useful” Models of SiO2-CaO-Al2O3 T-x-y Diagram

V. Lutsyk, A. Zelenaya

Physical Problems Department, Buryat Scientific Centre of RAS (Siberian Branch)

Existing T-x-y diagram models of СaО-Аl2О3-SiО2 system solve the distinct applied tasks, but have the significant disagreement with the topological structure. In particular, the immiscibility surfaces and four liquidus surfaces (3CaO×SiO2, 3CaO×2SiO2, 3CaO×Al2O3, CaO×6Al2O3) are absent in V. Danek’s thermodynamical model [1, P. 147]. In the model of R.Berman and T.Brown [2] one liquidus surface (5CaO×3Al2O3) is internal and doesn’t adjacent to the binary system CaO-Al2O3, in distinction to the experimental data. The model of K.Shobu, calculated by the thermodynamics software CaTCalc [3], doesn’t consider three liquidus surfaces (3CaO×SiO2, 3CaO×2SiO2, 5CaO×3Al2O3). In our work, a kinematical method of diagram surfaces description [4] is used for the simulation of computer model СaО-Аl2О3-SiО2. In this case, the surface is given by the motion of the forming line along to the directing lines, described by the interpolating polynomials. The coordinates of binary and ternary points as well as the points defining the curvatures of lines on the contour surfaces and the surfaces themselves were used as an initial data for model realization. The obtained model is formed by 15 liquidus surfaces, an immiscibility surface, 80 ruled surfaces, 16 horizontal complexes at the temperature of invariant points and 16 vertical planes of triangulation; and it involves 33 two-phase regions and 46 three-phase ones. Such model makes possible to consider the boundaries of two- and one-dimensional concentration fields with the different unique crystallization schemes, and to visualize the phase’s trajectories in any diagram part with the decoding of crystallization stage on the mass balance diagrams. Comparing different phase diagrams models for the same ternary system, it has been confirmed once more, that “All models are wrong, but some are useful” [5].

Key words: computer model, СaО-Аl2О3-SiО2 system, kinematical method, crystallization paths.

[1] Danek V. Physico-chemical analysis of molten electrolytes. Elsevier. 2006. [2] Berman R.G., Brown T.H. // Geochimica et Cosmochimica Acta. 48 (1984) 661. [3] Levin E.M., Robbins C.R., McMurdie H.F. Phase diagrams for ceramists. Ohio: American. Ceramic Society. 1964. [4] Shobu K. // CALPHAD. 33 (2009) 279. [5] Lutsyk V.I., Zyryanov A.M., Zelenaya A.E. // Russ. J. Inorg. Chem. 53 (2008) 792. [6] Gaune-Escard M. // Molten Salts & Ionic Liquids Bulletin. 98 (2009) 1.

134


[P17]Thermodynamic analysis of the inclusions formation in steels

for the automotive industry

W. V. Bielefeldt*, A. C. F. Vilela

Iron and Steelmaking Laboratory/LASID, Federal University of Rio Grande do Sul – UFRGS, Technology Center, Av. Bento Gonçalves 9500, CEP 91501-970 PO Box 15021, Porto Alegre, RS, Brazil

*e-mail: [email protected]

Introduction and goals: At present days, there are higher quality requirements for the production of special steels, remarkably those intended for automotive industry. Furthermore, such steels are considered critical in relation to their production by continuous casting (CC) process, since contents of elements such as Al, S, Ca, and O must be controlled. Steels for automotive parts need to have improved machinability and mechanical properties (grain size and fatigue resistance). In this sense, the production of aluminium killed, high sulphur steels is increasing. Concerning continuous casting process, many factors have influence on steel castability, such as: refractory materials, slag composition, steel covering in the tundish, valve material and design, temperature control during the process, waiting times, among others. The control of inclusions is only one among these factors; however, it is very important for improving castability. Calcium alloys are widely employed to control composition, distribution and morphology of oxide and sulfide inclusions in steels. The computational thermodynamics shows to be an excellent tool for comprehending physico-chemical phenomena which occur in steelmaking, and, moreover, it can help engineers from industrial plant taking decision. The general purpose of this work is the thermodynamic study of non-metallic inclusions in the CC tundish for SAE 1141 and SAE 8620 steels. The specific purposes are: 1) obtaining the phases formed and their composition in inclusions by applying computational thermodynamic (FactSage); and 2) establishing conditions of steel composition for the improvement of steels castability.

Materials: SAE 1141 quality combines both good conformability and machinability in the same steel grade. It is widely employed in forging segments to produce components with both relative complexity and mechanical demand, such as forks and shaft ends for automotive industry. SAE 8620 steel is classified by SAE-AISI as nickel-chromium-molybdenum steel, which is a low alloy steel, used in components under the cementation process. SAE 8620 steel makes part of a series of steels for cementation, which have sufficient hardenability to be oil-quenched, acquiring, in their core, good values of ductility. They are employed for gear building sets, pieces for light works, small mechanisms, pins, etc, generally, materials which present as the most important characteristic wear resistance.

Methodology: Thermodynamic simulations were performed with the commercial software FactSage 5.5 and databases (FToxid and FSstel). Simulations were carried out by using both global chemical composition and average temperature of liquid steel in the CC tundish. The result obtained is the steel composition and non-metallic inclusions (oxides and sulfides) at the temperature of 1,520oC (SAE 1141) and 1,540oC (SAE 8620).

Results: Curves obtained in the figures (resulting in castability or liquid window): Calcium-aluminates saturation line (CaO.Al2O3, CaO.2Al2O3), considering a minimum of 30 and 35% of CaO in inclusions, CaS saturation lines: maximum of 5 and 10% of CaS, Lines of starting liquid, 40% and 100% of liquid phase in inclusions.

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Fig. 1 Liquid window for SAE 1141 steel and liquid phase formation, Total oxygen = 24.5 ppm; S = 0.101%

and T = 1,520 °C.

Fig. 2 Liquid window for SAE 8620 steel, including formation curves of liquid fraction and CaO.Al2O3,

Total oxygen = 18.0 ppm; S = 0.025% and T = 1,540 °C.

Conclusions: For SAE 1141 steel conditions, 10 - 45 ppm Al, there is a great difference between formation curves of 35% CaO, and the points of liquid fraction. However, from 45 ppm Al, they coincide. For Al = 50 ppm, there is not 2CaO.Al2O3.SiO2 formation, and the liquid phase starts with lower calcium content. However, for Al = 80 ppm, formation of CaO.Al2O3 occurs, backing to increase the calcium content necessary to form the liquid phase. Both conditions of chemical composition for obtaining window of liquid inclusions and the influence of aluminum content on forming inclusions for SAE 1141 steel were evaluated satisfactorily. For an average Al content of 275 ppm for SAE 8620 steel, inclusions window with a minimum of 35% of CaO and a maximum of 5% of CaS is between 10.9 and 14.2 ppm of calcium. The curve of 35% of CaO from SAE 8620 steel liquid window practically coincides with the initial formation of the liquid phase. One can observe modification of alumina inclusions by calcium, forming varied calcium-aluminates for different contents of Al and Ca under SAE 8620 steel conditions. Curves of liquid windows normally starts with Al contents higher than 100 ppm (indicating Al-killed steels), because it is from this value, the calcium-aluminates formation becomes predominant. As a general conclusion, a very good correlation was obtained between the thermodynamic predictions carried out in this study and the results obtained from the castability index of SAE 1141 and SAE 8620 steels produced by the continuous casting in the industrial plant. Thus, this research can contribute for the study of inclusions in other critical steels, as the employment of the methodology proposed here.

Keywords: inclusions; calcium; castability; computational thermodynamic; FactSage.

[1] Bielefeldt, W. V.; Vilela, A. C. F.: Computational Thermodynamic Study of Inclusions Formation in the Continuous Casting of SAE 8620 Steel. Steel Research International. v. 81, p. 1064-1069, 2010. DOI: 10.1002/srin.201000057. [2] Bielefeldt, W. V.; Vilela, A. C. F.; Moraes, C. A. M.; Fernandes, P. C.: Computational Thermodynamics Application on the Calcium Inclusion Treatment of the SAE 8620 Steel. Steel Research International, v. 78, p. 857-862, 2007. [3] Bielefeldt, W. V.; Vilela, A. C. F.: Thermodynamic Study of Non-Metallic Inclusion Formation in SAE 1141 Steel. In: 1º TMS-ABM Congress, 2010, Rio de Janeiro. 1º TMS-ABM Congress, 2010. p. 4474-4483.

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CALPHAD assessments

137


[P18]Thermodynamic Assessment of the Ni-Sn-X (X=In, Sb) Ternary Systems

Adela Zemanova1, Ales Kroupa1, Ratikant Mishra2, Herbert Ipser2, Hans Flandorfer2

1Institute of Physics of Materials, Academy of Sciences of the Czech Republic, Zizkova 22, 616 62 Brno, Czech Republic

2Department of Inorganic Chemistry / Materials Chemistry, University of Vienna, A-1090 Wien, Austria

The In-Ni-Sn and Ni-Sn-Sb alloys are potential candidates of the Pb-free solders, where Ni is used as substrate material in electronics. The aim of the present study is to develop the thermodynamic descriptions of the In-Ni-Sn and Ni-Sn-Sb ternary systems using the CALPHAD method. Phase equilibria in the ternary systems have been studied using X-ray powder diffraction, electron microprobe analysis, scanning electron microscopy and thermal analyses. All these experimental results and data from the literature were used for a CALPHAD-type optimization of In-Ni-Sn and Ni-Sn-Sb ternary systems. The unary data were taken from new version of SGTE (4.4) database. The thermodynamic data for binary systems used in these assessments are taken from the SOLDERS thermodynamic database. The complete solubility was found between Ni3Sn2 and Ni2In phases in the In-Ni-Sn ternary system and between Ni3Sn2 and NiSb phases in the Ni-Sn-Sb system, which are of the Ni2In and NiAs type, respectively. Therefore, identical thermodynamic model has to be used for these phases, with respect to the existing experimental data and previous description of these phases within the SOLDERS thermodynamic database.

Acknowledgement: The authors are grateful to the Ministry of Education of the Czech Republic (projects No. OC08053 and MEB 061005) for financial support.

Key words: Thermodynamic database, phase diagram, Pb-free solders, CALPHAD method.

138


[P19]The Study of Z-Phase in Ternary Cr-Nb-N and Cr-V-N Systems

Ales Kroupa, Adela Zemanova, Dominik Legut

Institute of Physics of Materials, Academy of Sciences of the Czech Republic, Zizkova 22, CZ-616 62 Brno, Czech Republic

The presence of Z-phase - the Cr2(Nb,V)2N2 nitride - in modern Cr-Mo steels is of crucial importance and influences significantly the mechanical properties of such materials. Good thermodynamic description of such phases is very important for complete thermodynamic assessment of multicomponent systems and reliable prediction of properties of complex advanced materials. Therefore the experimental and theoretical study of Cr-Nb-N and Cr-V-N systems is important to obtain more detailed information about these systems and, if possible, their proper thermodynamic description. The samples of above mentioned system were annealing for a long time to obtain states close to thermodynamic equilibrium and the experimental results were used in combined CALPHAD and ab-initio approach to describe above mentioned Cr-X-N systems, as they are crucial for Z-phase and plays important role in modeling of phase equilibria in advanced steels.

Acknowledgement The authors are grateful to the National Science Foundation of the CR (project No. 106/10/1908) and to Academy of Sciences of the Czech Republic No. AV0Z20410507

Key words: Z-phase, CALPHAD modelling, experimental study.

139


[P20]Diffusion multiples for subsystems within the Fe-Al-C-Mn system

Bonnie Lindahl, Malin Selleby

KTH, Royal Institute of Technology

Due to their outstanding mechanical properties, there is an increasing interest in TWIP (TWinning Induced Plasticity) steels and their low density, high aluminium counterpart L-IP (Lightweight steels with Induced Plasticity). The combination of high strength, high ductility and low density is of special interest in the automotive industry where the demand for inexpensive and environmentally friendly materials has increased drastically. The TWIP steels contain high amounts of manganese and the L-IP steels contain high amounts of aluminium as well. In the present work alloys with up to 40 mass% manganese and 15 mass% aluminium are being studied. The high interest in these steels gives rise to a demand forbetter knowledge of the thermodynamic properties of the relevant systems. Conventional steels only contain low amounts of Mn and Al therefore the existing databases are not adequate. In phase diagram determination, diffusion multiples are very handy for determining phase relations in systems. In this work re-assessments of some of the subsystems in the quaternary system Al-Fe-Mn-C were done using diffusion multiples and equilibrium annealing guided by simulations of diffusion paths.

Key words: Assessment, CALPHAD, Fe-Al-C-Mn, Diffusion multiples.

140


[P21]First-principles calculations and thermodynamic assessment

of the Te-Zr system

Changjun Wu1, Xuping Su2, Jianhua Wang2, Ya Liu2, Haoping Peng1, Hao Tu2

1Key Laboratory of Materials Design and Preparation Technology of Hunan Province, Xiangtan University, Hunan, P.R. China,

2Key Laboratory of Advanced Metal Materials of Changzhou City, Changzhou University, Changzhou, Ji-angsu, P.R. China

The Te-Zr binary system was thermodynamically assessed by the CALPHAD approach with the help of first-principles calculations. First-principles calculations of the energies of formation of seven Te-Zr compounds were performed using the Vienna Ab-initio Simulation Package (VASP). The enthalpies of formation of Te5Zr, Te3Zr, Te2Zr, Te6Zr5, TeZr, Te4Zr5 and TeZr3 are -51.7 KJ/mol atom, -69.7 KJ/mol atom, -88.5 KJ/mol atom, -88.2 KJ/mol atom, -87.6 KJ/mol atom, -83.7 KJ/mol atom and -49.1 KJ/mol atom, respectively. The calculated enthalpy of formation of Te2Zr and Te4Zr5 agrees well with experimental data. The optimization of the Te-Zr system was performed by PARROT module using available experimental data from literature. The Gibbs free energy of the liquid was described by a sub-regular solution model with the Redlich-Kister equation. And all the Te-Zr binary compounds except Te2Zr are stoichiometric ones. The Te2Zr was described by two-sublattice model (Te)1(Te,Zr)2. The enthalpies of formation obtained by first principle calculation were used as input data in evaluating the Gibbs energy functions of those phases. The thermodynamic parameters were optimized to consistently reproduce the available experimental data with satisfactory agreement.

Acknowledgement: The financial support from Qinlan project and National Natural Science Foundation of China (Nos. 50971110 and 50971111) are greatly acknowledged.

Key words: Te-Zr, CALPHAD, first-principle, phase diagram.

141


[P22]Thermodynamic Modeling of the Ba-Mg binary system

Xin Ren, Changrong Li*, Zhenmin Du, Cuiping Guo, Sicheng Chen

School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China


On the basis of the thermochemical and phase equilibrium experimental data, the phase diagram of the Ba-Mg binary system has been assessed by the CALPHAD technique. The liquid phase is of unlimited solubility and modeled as a solution phase using the Redlich-Kister equation. The intermetallic compounds, Mg17Ba2, Mg23Ba6 and Mg2Ba, with no solubility ranges are treated as strict stoichiometry compounds by the formula MgmBan. Two terminal phases, hcp-Mg and bcc-Ba, are kept as two pure element phases, since Mg and Ba do not dissolve in one another. After optimization, a set of self-consistent thermodynamic parameters has been obtained. The calculated values agree well with the available experimental data.

Keywords: Ba-Mg system; Thermodynamic assessment; CALPHAD technique.

Fig. 1. Calculated Ba-Mg phase diagram by the present thermodynamic description and comparison with the experimental data: (a) Entire phase diagram; (b) Enlarged section.

Acknowledgments: The authors would like to acknowledge National Natural Science Foundation of China (No. 50731002 and No. 50671009) for the financial support. Thanks to Royal Institute of Technology and CompuTherm LLC for supplying Thermo-Calc and Pandat Software packages respectively.

142


[P23]Thermodynamic modeling of the Ge-La binary system

Miao Liu1,2, Changrong Li1*, Zhenmin Du1, Cuiping Guo1, Chunju Niu1

1 School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China

2 The 3r4 department, Institute of Chemical Defense of P. L. A., Beijing 102205, China *e-mail: [email protected]

The Ge-La binary system was critically assessed by means of the CALculation of PHAse Diagram (CALPHAD) technique. The liquid phase with unlimited solubilities of Ge and La into each other and the terminal solid solution diamond-(Ge) with a small solubility of La were described using the substitutional model, in which the excess Gibbs energy was formulated with the Redlich-Kister equation. The compounds with homogeneity ranges, αGe1.7La, βGe1.7La and GeLa, were modeled using two sublattices as α(Ge, La)1.7La, β(Ge, La)1.7La and (Ge, La)(Ge, La) respectively. The intermediate phases with no solubility ranges, Ge4La5, Ge3La4, Ge3La5 and GeLa3, were treated as stoichiometric compounds. The three allotropic modifications of La, dhcp-La, fcc-La and bcc-La, were kept as pure element phases since there is no solubility of Ge in La. A set of self-consistent thermodynamic parameters of the Ge-La binary system was obtained. The calculation results agree well with the available experimental data from literatures.

Keywords: Ge-La binary system; Thermodynamic assessment; CALPHAD technique.

Fig. 1. The Ge-La binary phase diagram compared with experimental data.

Fig. 2. Calculated partial molar enthalpies of La in liquid at 1892~1905K.

Acknowledgements: Thanks to the Royal Institute of Technology Sweden for supplying the Thermo-Calc software. The authors would like to acknowledge National Natural Science Foundation of China (No. 50731002 and No. 50671009) for the financial support. Thanks also to Dr. Viktor Kusnetsov from Lomonosov Moscow State University for literature collection.

143


[P24]Experimental Study of the Al-Ni-Pt Alloy System

D. Kapush1, K. Korniyenko1, V. Petyuch1, T. Velikanova1, V. Shemet2, B. Grushko3

1I.N. Frantsevich Institute for Problems of Materials Science 2IEK-2, Forschungszentrum Jülich GmbH, D-52425 Jülich 3PGI-5, Forschungszentrum Jülich GmbH, D-52425 Jülich

Pt-modified nickel aluminide coatings are used in order to improve the high-temperature oxidation resistance of the components of the gas turbines produced from Ni-based superalloys. This explains an interest in the low-Al part of the Al-Ni-Pt system. On the other hand, the interest in the Al-rich part is because of the formation of complex periodic and quasiperiodic intermetallics attractive for both basic and applied research. In our work we present phase equilibria in the Al-Ni-Pt alloy system investigated at 1100 and 1300 °C as well as in the temperature range of crystallization in the whole compositional range and also at 1000, 900 and 790 °C from 50 to 100 at. % Al using SEM/EDX, XRD and DTA. The liquidus and solidus surfaces, reaction scheme as well as isothermal sections at the aforesaid temperatures are constructed. 17 invariant four-phase reactions with participation of liquid were determined. The Al2Pt phase was found to extend up to ~Al53Ni23Pt24 composition, separating the Al3Pt2 and Al3Ni2 phase fields. Isostructural AlNi and high-temperature AlPt phases are probably formed continuous region of solid solutions at elevated temperatures. Four ternary phases were revealed: two of them - in the Al-rich region, namely the χ phase (~ Al73Ni7Pt20, rhombohedral structure, a = 1.20953(25), c = 2.6932(4) nm, the Al28Ir9-type) and the e phase (~Al72Ni12Pt16, the ε6-type orthorhombic structure, a = 2.34, b = 1.65, c = 1.24 nm). Apart from the ternary structure of the before known AuCu-type also its C-centered orthorhombic superstructure (Pt5Ga3-type structure) was revealed along ~35 at. % Al. Its lattice parameters for the Al33.5Ni7.2Pt59.2 composition are a = 0.79022(10), b = 0.72583(8), c = 0.39319(5) nm. At 1100 and 1300 °C it coexists in a wide compositional range with the ternary extension of the low-temperature AlPt and AlNi(Pt) β-phase.

Key words: SEM/EDX, XRD and DTA.

144


[P25]Thermodynamic modelling of the LaNi(5-x)AlxHy (0< x < y)

E. R. Pinatel1, M. Palumbo2, P. Rizzi1, M. Baricco1

1Università di Torino 2ICAMS, Ruhr University Bochum

The system LaNiH is well known for hydrogen storage applications. A dehydrogenation enthalpy of about 30 kJ/mol H2 allows the release of hydrogen close to room temperature and under 1 bar. This system alone already shows good properties for hydrogen storage applications but Ni can be partially substituted with other elements in order to tune the adsorption-desorption behaviour and to improve cyclability[1]. Al is one of the best substituents because it shows a solubility up to LaNi3.5Al1.5, it is able to significantly reduce the disproportionation/decomposition of the hydride and to lower the plateau pressure[2,3]. For these reasons, the thermodynamic behaviour of the Ni-Al substitution in LaNi5 is of particular interest. The aim of this work is to extend the CALPHAD description of the La-Ni-H system[4] in order to model the LaNi(5-x)

AlxHy solid solution. The system was investigated experimentally by means of PCI (Pressure Composition Isotherm) for several temperatures (25, 40, 60, 80 and 100°C) and for different Al contents (x = 0, 0.2, 0.4, 0.6 and 0.8).Samples were prepared by arc melting and checked by X-ray powder diffraction, SEM (scanning electron microscope) and EDS (Energy Dispersive X-ray Spectroscopy) analysis. According to structural information[2], a 3 sublattices model (La)(Ni,Al)5(H,Va)7 has been chosen to describe the solid solution. First principles calculations using Density Functional Theory (DFT) were performed to estimate the formation energies of the end-members (LaAl5 and LaAl5H7). The calculations employed the generalized gradient approximation of Perdew-Burke-Ernzerhof (PBE) as implemented in the VASP code with PWS pseudopotentials. The free energy of the solid solution as a function of composition and temperature was assessed from data available from experiments, first principles calculations and literature using the CALPHAD approach. The assessed thermodynamic functions for this phase show a good agreement with available experimental data.

Key words: LaNi5-xAlxHy, LaNi5, Hydrogen storage, CALPHAD assessment, thermodynamic modelling.

[1] H.H. Van Mal, K. H. J. Buschow and A.R. Miedema, J. of the Less Common Metals,35 1(1974) p.65. [2] H. Diaz, A. Percheron-Guйgan, J.C. Achard, C. Chatillon and J.C. Mathieu, Int. J. of Hydrogen Energy,4 5(1979) p.445. [3] Y. Hashimoto, K. Asano and Y. Iijima, Materials Transactions,43 11(2002) p.2696. [4] M. Palumbo, J. Urgnani, D. Baldissin, L. Battezzati and M. Baricco, Calphad,33 1(2009) p.162.

145


[P26]Effect of Basicity on the Chromium Partition in CaO-MgO-SiO2-Cr2O3

Synthetic Slag at 1873 K

Galina Jelkina, Lidong Teng, Bo Björkman

KTH Royal Institute of Technology, Stockholm, Sweden

The objective of the present work is to get an understanding of the phase relationships in the CaO-MgO-SiO2-Cr2O3 slags with a view to control the precipitation of Cr-spinel in the slag phase. It was reported that Cr in the spinel phase has lower leaching levels than in some silicate phases. The equilibrium phases in CaO-MgO-SiO2-Cr2O3 slag system at 1873 K have been studied. The Cr2O3 and MgO contents in the slag were fixed to 6wt% and 8wt% respectively. The basicity (CaO/ SiO2) of slag was changed in the range of 1.0 to 2.0. Gas/slag equilibrium technique was adopted to synthesize the slag at high temperature in air atmosphere. The samples were heated to and held at 1873 K for 24h in order to achieve the equilibrium state. Thereafter the samples were quenched in air. The chromium distribution and phase compositions were studied using SEM, EDS and XRD techniques. FACTsage software was used for the phase equilibrium calculations. The experimental results obtained from the present work were compared with the calculation results from FACTSage software. It is found that the spinel formation at 1873 K is favored in the slag basicity range of 1.2 to 1.6.

Key words: Phase equilibrium, slag basicity, spinel, Cr2O3, SEM, XRD.

146


[P27]Thermodynamic assessment of Ca-Cu-Mg sytem

Guoxing Huang, Haiying Qi, Libin Liu*, Zhanpeng Jin

School of Materials Science and Engineering, Central South University, Changsha Hunan 410083, P.R.China *e-mail: [email protected]

Bulk metallic glasses (BMGs) research has been a hotspot since the metal-metal system such as Ca-,La-,Mg-,Zr-based alloys were prepared by stabilization of supercooled liquid. And the glass formation ability (GFA) is vital to develop new BMGs. Thus the Scientific efforts have been done to assess GFA. One of the successful approaches is using CALPHAD method to calculate the onset driving force (ODF) for crystalline phases from supercooled liquid. The purpose of this paper is to bulid up the thermodynamic database of Ca-Cu-Mg and predicts the glass formation composition range. All the binary parameters come from our group’s Magnesium alloy database and the ternary parameters derived from experiments of Myles [1] and Sommer[2]. Fig.1 and Fig.2 show that the calculated results are agree with the experiments. Therefor the built up thermodynamic data is reasonable to calculate the ODF. The glass formation of Ca-Cu-Mg had been studied by many authors [3-6]. The iso-ODF of Ca-Cu-Mg is showed in Fig.3 comparing with the range of complete glass formation [3]. It indicates that the low ODF is the most important factor to form the glass metal.

(a) (b)

Fig.1 Calculated the mixing enthalpy of Liquid wih experiments.

Fig.2 Calculated the isthermal section at 623K. Fig.3 Calculate the iso-ODF lines for the whole composition.

[1] Myles, K.M., The ternary system copper-magnesium-calcium. Journal of the Less Common Metals, 1970. 20(2): p. 149-154. [2] Sommer, F., H.G. Krull, and J.J. Lee, Calorimetric studies of liquid Ca-Cu-Mg alloys. Journal of the Less Common Metals, 1991. 169(2): p. 361-368. [3] Sommer, F., W. Vogelbein, and B. Predel, Glass formation of ternary Ca-Cu-Mg alloys. Journal of Non-Crystalline Solids, 1982. 51(3): p. 333-343. [4] Mizutani, U., et al., Electronic structure and electron transport in Ca-Mg-Cu metallic glasses. Materials Science and Engineering, 1988. 99(1-2): p. 295-299. [5] Laws, K.J., et al., Synthesis of copper-based bulk metallic glasses in the ternary Cu-Mg-Ca system. Journal of Alloys and Compounds, 2009. 486(1-2): p. L27-L29. [6] Laws, K., et al., Prediction of Glass-Forming Compositions in Metallic Systems: Copper-Based Bulk Metallic Glasses in the Cu-Mg-Ca System. Metallurgical and Materials Transactions A, 2010. 41(7): p. 1699-1705.

147


[P28]Application of the molecular interaction volume model to Phase diagram

calculations of Fe-Ni and Fe-Co systems

Hongwei Yang, Yijun Wang, Dongping Tao

Kunming University of Science and Technology, Yunnan, PR China

We calculate the phase diagrams of Fe-Ni and Fe-Co systems by means of a combination of the molecular interaction volume model (MIVM) calculations and the CALPHAD approach. The molecular interaction volume model (MIVM) was obtained on a physical basis. It is a two-parameter model and is able to predict component activities and enthalpies in liquid alloys and solid solutions at the required temperatures. A significant advantage of the MIVM lies in its ability to calculate thermodynamic properties of multicomponents alloys using only the binary infinite dilute activity coefficients. It, therefore, avoids empirical fitting for the pair potential energy interaction parameters. Using the obtained thermodynamic data of every phase in the systems, the Gibbs energy of solution phases and compounds optimized in every system were calculated using the MIVM. The Fe-Ni and Fe-Co phase diagrams and some correlated thermodynamic properties were calculated. The results are in agreement with the experimental data and then indicate that the model is reliable and convenient.

Key words: molecular interaction volume model, Phase diagram calculations, thermodynamic model, CALPHAD approach.

[1] D.P. Tao, Thermochim. Acta. 363 (2000) 105-113. [2] D.P. Tao, B. Yang, D.F. Li, Fluid Phase Equilibria, 193 (2002) 167-177. [3] H. W. Yang, D. P. Tao, Metall. Mater. Trans. A, 39 (2008) 945-949. [4] H. W. Yang, D. P. Tao, Q. M. Yuan, Y. Yang, Fluid Phase

148


[P29]Thermodynamic assessment of LiCl-UCl3 and KCl-UCl3 binary systems

by coupling CALPHAD and first principles calculations

K.C. Hari Kumar1, Suddhasattwa Ghosh2, B. Prabhakara Reddy2, K. Nagarajan2, P.R. Vasudeva Rao2

1Department of Metallurgical and Materials Engineering, Indian Institute of Technology, Madras, 600 036, Chennai, Tamil Nadu, India,

2Fuel Chemistry Division, Chemistry Group, Indira Gandhi Centre for Atomic Research, Kalpakkam, Tamil Nadu, 603 102, India

We report on the thermodynamic assessment of LiCl-UCl3 and KCl-UCl3 carried out by combining CALPHAD and ab initio methods. The liquid and solid solutions were modelled by ionic two-sublattice model. The enthalpy of mixing in these systems was calculated using the surrounded-ion model for asymmetric molten salt systems [1-4] and were found to be within ±8 %. The enthalpy of formation of K2UCl5 which is a congruently melting compound in KCl-UCl3 system was calculated using a full potential linearized augmented plane wave+local orbital method as implemented in Wien2k [5] using generalized gradient approximation within the framework of density functional theory. The spin orbit coupling was included by applying the second variational procedure for the scalar relativistic eigenstates, for which the basis was extended by relativistic 6p1/2 local orbitals centered at U atom for all spin orbit calculations. The number of k-points in the irreducible Brillouin zone and RKmax were taken to be 1248 and 7.00 respectively where R is the smallest muffin tin radius taken to be 2.5 and Kmax is the largest k-vector in the reciprocal lattice used in the plane wave basis set expansion. The number of k-points and Kmax were sufficient enough to achieve a self consistent total energy value with an energy convergence criteria of 0.01 mRy and also until the difference in the charge between the successive iterations was less than 0.0001 electrons. Since the molecular species could not be directly trea

Key words: Salt systems, LiCl-UCl3, KCl-UCl3, optimization, ab initio, surrounded-ion model.

[1] M.Gaune-Escard, J.C.Mathieu, P.Desre, Y.Doucet, J.Chim.Phys., 6 (1973) 1003. [2] M.Gaune-Escard, J.C.Mathieu, P.Desre, Y.Doucet, J.Chim.Phys., 7-8 (1973) 1033. [3] G.Hatem, M.Gaune-Escard, J.Chim.Phys., 4 (1975) 463. [4] G.Hatem, M.Gaune-Escard, J.Chim.Phys., 77 (1980) 925. [5] P.Blaha, K.Schwarz, G.K.H.Madsen, D.Kvasnicka, J.Luitz, “WIEN2k, An augmented plane wave +local orbitals program for calculating crystal properties “, 2001, ISBN-3-9501031-1-2.

149


[P30]Investigation of the phase diagrams and microstructure evolution

of Al-Cu-RE alloys

Libin Liu, Ligang Zhang, Hong Bo, Zhanpeng Jin

School of Materials Science and Engineering, Central South University, Changsha Hunan 410083, P.R.China


Interest in aluminum alloys is increasing continuously due to their properties such as the low density, high strength, high corrosion-resistance as well as their potential applications in the automotive and aerospace industries. Microalloying has been used to improve the high temperature strength of the selected age hardening aluminum alloys. Rare earth elements are benefit to casting process in the conventional aluminum alloys resulted in improving tensile strength, heat resistance and corrosion resistance, etc. for many years. The invesitagiation on the glass forming ability (GFA), especially on the thermodynamic modeling of amorphous forming system, is an important issue on the amorphous alloys research. The key to the thermodynamic modeling of GFA of alloys is the reliable binary and ternary phase diagram and thermodyniac properties. Associated with a project entited “Investigation of phase diagram and microalloying of Al-Cu based alloy systems” supported by National Science Foundation of China (No. 50771106), the Cu-RE (RE=Y, Nd, Gd and Dy) binary systems and Al-Cu-X (X=Dy, Er, Gd, Nd, Sc, Ti, Y, Yb, Zr) systems have been investigated by means of experimental determination and CALPHAD method. The experimental result showed that Cu7RE phase forms in the Cu-rich region of the Cu-Y and Cu-Dy binary systems, and in Cu-Y and Cu-Dy binary systems the Cu-rich compounds are Cu6RE phases. It was shown that Cu7Dy phase was only stabilized at high temperature, this phase was decomposed to Fcc(Cu)+Cu5Dy_L in low temperature. A ternary compounds(τ1-Al8Cu4Er) and six ternary compounds (τ1 -Al8Cu4Nd, τ2-Al9Cu8Nd2, τ3-Al6Cu7Nd, τ4-Al2.4Cu8.6Nd, τ5 -Al3CuNd and τ6-AlCuNd) were determined in the Al rich part of the isothermal 673 K section of the Al-Cu-Er and Al-Cu-Nd systems. Based on the experimental phase relations and literature results, the thermodynamic parameters of the Cu-Gd, Cu-Dy, and Cu-Er binary systems and the Al-Cu-X (X=Dy, Er, Gd, Nd, Sb, Sc, Ti, Y, Yb, Zr) ternary systems have been obtained. In order to verify the quality of the thermodynamic parameters, the electric-arc melted cast-state sample of Al-Cu-MM (MM=Y, Nd, Gd, Dy, Er and Ti) were prepared. The equilibrium solidification and the solidification according to the Scheil model were calculated for the alloys. The calculated results were successfully applied to understand the experimental microstructures of the above mentioned alloys in Al-Cu-MM (MM=Y, Nd, Gd, Dy, Er and Ti) system. Based on the thermodynamic database, the relationship between the GFA and the driving forces of crystalline phases was investigated. It was revealed that the alloys with good glass forming ability in the Al-Cu-RE system have the low driving forces of the crystalline phases. These minimum driving forces are the criterion for selecting the composition for formation of Al-Cu-MM amorphous alloys.

Key words: Al-Cu-RE, CALPHD approach, Alloy design, Equilibrium phase diagram, Solidifction simulation, Glass forming ability.

150


[P31]Modeling of Thermodynamic Properties and Phase Equilibria in

Mg-Al-Mischmetal Systems

Liling Jin1, Youn-Bae Kang2, Patrice Chartrand1, Aimen Gheribi1, Dmytro Kevorkov3, Mamoun Medraj3

1Center for Research in Computational Thermochemistry (CRCT), Dept. of Chemical Engineering, Ecole Polytechnique de Montréal,

2Institute for Ferrous Technology, Pohang University of Science and Technology, 3Department of Mechanical Engineering, Concordia University

Magnesium - aluminum - based alloys are widely used because of their low density, high strength-to-weight ratio, specific rigidity, satisfactory salt-spray corrosion resistance and good ductility. Adding misch-metal to Mg-Al alloys, which is a mixture of rare earth (RE) elements with typical composition ranges of La (25-34%), Ce (48-55%), Pr (4-7%) and Nd (11-17%) [1], may improve the creep resistance [2] and strength at elevated temperatures due to the precipitation of the intermetallic phases (like Al11RE3 and Al2RE phases), and suppression of probably detrimental Mg17Al12 phase in the interdendritic or grain boundary region. The aim of current study is to optimize or predict the thermodynamic properties and phase diagrams of Al-RE (La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu), Mg-Al-RE (La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho and Er) systems and Al-RE’-RE’’ and to build a complete thermodynamic database concerning Mg, Al and RE elements, which will guide the magnesium and aluminum alloys design. Optimized model parameters of the Gibbs energies for all phases in these systems have been obtained. The optimization procedure is biased by putting a strong emphasis on the observed trends in the thermodynamic properties of Al-RE, Al-Mg-RE, Al-RE’-RE’’ systems, like enthalpy of formation, enthalpy of mixing. The Modified Quasichemical Model [3], which takes short-range ordering into account, is used for the liquid and the Compound Energy Formalism is used for the solid solutions in the binary systems. Equilibrated key alloys experiments are carried out for Mg-Al-(Ce, La, Nd) systems in order to validate the modeling parameters. Furthermore, first-principles calculations using VASP software are performed for the partial enthalpies of mixing in the Al- (Ce, La, Pr, Nd) and Mg- (Ce, La, Pr, Nd) binary systems and the modified Miedema’s model, are used to calculated the enthalpies of formation of the binary ternary intermetallic compounds.

Key words: Thermodynamic.

[1] J. Gnobner and R. Schmid-Fetzer. Thermodynamic modeling of the Mg-Ce-Gd-Y system. Scripta Materialia 63 (2010): 674-679. [2] G. Pettersen, et al. Microstructure of a pressure die cast magnesium--4wt.% aluminium alloy modified with rare earth additions. Materials Science and Engineering A 207 (1996): 115-120. [3] A. D. Pelton, et al. The modified quasichemical model I - binary solutions. Metallurgical and Materials Transactions B: Process Metallurgy and Materials Processing Science 31B (2000): 651-659.

151


[P32]Experimental investigation and thermodynamic modelling

of the Fe-Cr-Mo-C system

Luiz Eleno1, Márcio Gustavo di Vernieri Cuppari2, Cláudio G. Schön1

1Universidade de São Paulo 2Universidade Federal do ABC

A new assessment of the Fe-Cr-Mo-C quaternary system was performed, mainly to take into account new experimental information obtained recently by our group. Several alloys, with different compositions, were induction-melted under vacuum and later homogenized at 1170°C for 72 hours. The alloy compositions were determined by setting the Chromium content at 5 weight-% and varying the Carbon (0.5 - 1.5 w%) and Molybdenium (1 - 2 w%) ammounts. The alloys were then encapsulated in quartz and equilibrated at 600, 700 and 900°C. The thermodynamic optimization consisted in altering the parameters of the carbides from the TCFE database, especially the M23C6, while keeping all other parameters. A recent model for the cementite [1] was also incorporated into the assessment. The results shows a tendency to increase the stability of the M23C6 carbide over the M7C3, in agreement with the experimental information. A better overall agreement also resulted from the optimization.

Key words: Thermodynamics, Modelling, Assessment, Tool Steels, Fe-Cr-Mo-C, Experimental determination.

[1] B. Hallstedt et al., Calphad 34 (2010), 129.

152


[P33]Thermodynamic Modeling of the Binary System Co-Sm

Marcos Flavio de Campos1, Alexandre Bellegard Farina2

1Universidade Federal Fluminense 2Villares Metals S/A

In this study, it is described the Thermodynamic modeling of CoSm binary phase diagram using the CALPHAD (Calculation of Phase Diagrams) methodology. A detailed thermodynamic description of binary system Co-Sm was obtained, leading to a thermodynamic database compatible with experimental data from literature. Reliable Curie temperature for the phases Co2Sm, Co3Sm, Co7Sm2 ,Co19Sm5 ,Co5Sm, Co17Sm2

[1] provided consistent parameters for the calculated phase diagram. All phases were considered as line compounds, except the phases Co5Sm and Co17Sm2 . The sub-lattice model was employed for the thermodynamic description of all phases. The solubility of the Co17Sm2 phase was successfully modeled, obtaining values coherent with experimental data from literature. The model assumes that Sm replaces pair of Co atoms into Co17Sm2 structure. A model for the description of the solubility of Co5Sm phase has also been proposed. Taking into account experimental data [1], it is assumed that the solubility of Sm into SmCo5 is negligible, and that dumbbell substitution of Sm atoms by pairs of Co atoms account for the solubility of Co into SmCo5. The enthalpy of formation of the phase Co5Sm has been calculated: -8609J/mol. This value is in agreement with published experimental data [2]. A new model for the liquid phase was adopted in order to improve the description of recent experimental data.

Key words: Phase-diagram; Co-Sm; Thermodynamic modeling.

[1] Campos, M. F. de, Landgraf, F. J. G. J. Phase Equilibria v.21, n.5, pp. 443- 446, OCT 2000. [2] Meyer-Liautaud, F. Allibert, C. H. Castanet, R. Journal of Less- Common Metals, 127 (1987) pp. 243-250.

153


[P34]Experimental Study and Thermodynamic Assessment

of the ER-H Binary System

Aurore Mascaro 1, Jean-Marc Joubert 2, Caroline Toffolon-Masclet 1, Caroline Raepsaet 4

1CEA DEN/DANS/DMN/SRMA/LA2M France 2CNRS ICMPE/CMTR France

In order to increase cycle length and fuel burn up of pressurized water reactors (PWR), new fuel claddings are studied. In this framework, a new concept is being developed by the CEA: a cladding constituted by a liner of zirconium-erbium alloy between two liners of industrial zirconium alloys [1, 2]. Indeed, erbium, thanks to its high neutron absorption cross section, can be used as a solid burnable poison for controlling the nuclear reaction. This kind of configuration provides a more homogeneous power distribution within the reactor core and liberates some extra space for more fuel. Each cladding is surrounded by a pressurized water environment. Furthermore, some hydrogen released from the dissociation of water molecules diffuses inside the material. Thus, it is of high interest to have a good knowledge of the Er-H-Zr ternary system. In this study, the Er H system, one of the 3 constitutive binary systems has been studied experimentally and modelled by the Calphad method. The samples have been synthesised by hydrogenation using the Sieverts method. They have been analysed by X-ray diffraction and to quantify and locate the hydrogen, the nuclear microprobe has been used with PIXE + ERDA combination (Particule Induced X-rays Emission and Elastic Recoil Detection Analysis). Several pressure-composition isotherms have been measured, complementing the data available in the literature. This system has been modelled using the CALPHAD method. Due to the existence of homogeneity domains, the solid phases have been modelled with the sub-lattice model. Formation enthalpies of stable and metastable phases have been calculated ab-initio [3] and incorporated in the model. A set of parameters describing the Gibbs energies of the different phases is given and reproduces well the available experimental data.

Key words: Metal hydrides, Calphad assessment, ab-initio calculations, experimental measurements.

[1] Brachet, J.-C., and coll., 2006: French CEA patent: BD 1725. [2] Brachet, J.-C., and coll., Proceedings of Top Fuel 2009, paper 2189, Paris (France) September 6-10, 2009. [3] Joubert, J.-M., Mascaro, A., Crivello, J.-C and Toffolon-Masclet, Ab-initio calculations of Er-H compounds: application to the modelling of the phase diagram.

154


[P35]Prediction of Solubility from the Water Activities in the mixed Aqueous

Solutions YCl2 + Y’Cl2 + H2O with Y’; Y ≡ Mg2+; Ca2+; or Ba2+

Mohamed El Guendouzi*, Rachid Azougen, S. Mohammed Aboufaris E., Ihssane Hamdouny

Laboratoire de Chimie Physique, Faculty of Sciences Ben M’Sik, University Hassan II-Mohammedia-Casablanca, B.P 7955, Casablanca, Morocco


The thermodynamic computing models used for the prediction of behavior solutions solid -liquid- gas equilibria close to experimental accuracy have wide applicability. They can simulate the complex changes that occur in nature and can replicate conditions that are difficult to duplicate in the laboratory. Such models can be powerful predictive and interpretive tools to study the geochemistry of natural waters and mineral deposits, solve environmental problems, and optimize industrial processes. The specific interaction approach for describing electrolyte solutions to high concentrations introduced by Pitzer, represents significant advance in physical chemistry that has facilitated the construction of accurate thermodynamic models. These theory models of electrolyte solution have been developed by others authors, which reliably predict mineral solubility in the complex brine system. The main objective of this study is the development of a thermodynamic model for solution behavior and solid-liquid equilibria. In this investigation, the mixed aqueous solutions of chloride with alkaline earth metal {y YCl2 + (1-y) Y’Cl2} (aq) with Y; Y’ ≡Mg2+; Ca2+; and Ba2+ have been studied using the hygrometric method at 298.15 K. The water activities are measured at total molalities from 0.20 mol.kg-1 to saturation for different ionic-strength fractions y of YCl2 with y =0.20, 0.50 and 0.80. The obtained data allow the deduction of osmotic coefficients. From these measurements, the mixing ionic parameters θ YY’ and ψ Y’YCl are determined and used to predict the solute activity coefficients in the mixtures. The values of the pure electrolyte, mixing ionic -interaction parameters, which give the best fit of the activity data in binary, ternary solutions and solubility data. Thermodynamic characteristics, solubility products K°sp and the standard molar Gibbs energy of formation 0

f mG∆ of the crystallizing solids are determined. These systems magnesium, barium and calcium chloride minerals are the higher solubility minerals of the complex sea-salts and brine. Solid sea salt particles take up water in the atmosphere and form aqueous droplets. The prediction for electrolytic systems is the prerequisite before applying the software to the pilot and industrial processes, such as the wet-process phosphoric acid production at the industrial scale.

Keywords: Water Activity, Aqueous Solutions, hygrometric method, Solubility, thermodynamic models.

[1] Pitzer, K. S. Thermodynamics of electrolytes. I. Theoretical basis and general equations. J. Phys. Chem. 1973, 77, 268-277. [2] Harvie, C.; Moller, N.; Weare, J. The prediction of mineral solubilities in natural waters: The Na-K-Mg-Ca-H-Cl-SO4-OH-HCO3-CO3-CO2- H2O system from zero to high concentration at 25°C. Geochim.Cosmochim.Acta 1984, 48, 723-751. [3] Pabalan, R.; Pitzer, K. S. Thermodynamics of concentrated electrolyte mixtures and the prediction of mineral solubilities to high temperatures for mixtures in the system Na-K-Mg-Cl-SO4-OH-H2O. Geochim. Cosmochim. Acta 1987, 51, 2429-2443. [4] Christov, C.; Moller, N. Chemical equilibrium model of solution behaviour and solubility in the H-Na-K-OH-Cl-HSO4-SO4-H2O system to high concentration and temperature. Geochim.Cosmochim. Acta, 2004, 68, 1309-1331. [5] El Guendouzi, M., Errougui, A. Solubility in the ternary aqueous systems containing M, Cl-, NO3

-, and SO42- with M = NH4

+, Li+, or Mg2+ at T = 298.15 K, J. Chem. Eng. Data 2009, 54, 376-381. [6] Azougen, R., EL Guendouzi, M., Rifai, A., Faridi, J. Water activities, activity coefficients and solubility in the binary and ternary aqueous solutions LiCl +YCl2+ H2O with Y ≡ Mg2+; Ca2 +; or Ba2+, Calphad, 2010, 34,36-44. [7] Azaroual M., Kervevan C., Lassin A., André L., Amalhay M., EL Guendouzi M. Modeling and analysis of the thermodynamic conditions of mineral fouling in the wet-process phosphoric acid production (25 < T < 100°C). COVAPHOS III, Marrakech – Morocco March 18-20th, 2009.

155


[P36]Diffusion bonding in the Ag-Cu system

R. Novakovic

National Research Council (CNR) - Institute for Energetics and Interphases (IENI)

In this work theoretical results on the diffusion bonding in the Ag-Cu system are presented. Dissolution, growth and chemical solid phase diffusion are kinetic processes involved in the joining of similar materials. The joint formation is dependent on a number of parameters, in particular, time, bonding temperature, mutual solubility, diffusion rates of the diffusing components, applied pressure, and method of heat application. The computed results are compared with the results reported in the literature.

Key words: Diffusion.

156


[P37]Coupling compound energy formalism CALPHAD modeling with first principle

calculation for ionic materials

Shih-kang Lin, Dane Morgan

Department of Materials Sciences and Engineering, University of Wisconsin-Madison

Phases with homogeneity ranges are conventionally well described by the calculation of Phase Diagram (CALPHAD) approach using the Compound Energy Formalism (CEF). However, in ionic materials, the wide composition ranges are usually coupled with variety of valance states of constituent elements, which results in numerous compositional end-members in the CEF model. Moreover, most of these end-members are not charge neutral, ensuring that no direct measurements of these compounds can be obtained. In practice, determining the large number of model parameters in the CEF from typical experimental data sets requires many, often poorly justified, approximations. First principle calculations offer a way to reduce the approximations used in applying the CEF to complex ionic systems. Here we discuss approaches to treat the problems of modeling complex charged end-members to enable energetics from first principle calculation to be applied in the CALPHAD CEF in ionic systems. Initial results for La1-yMnO3±d perovskite, a base oxide for many important cathode materials in solid oxide fuel cells and other applications, will be presented.

Key words: CALPHAD, compound energy formalism (CEF), density functional theory (DFT), ionic materials, LaMnO3.

157


[P38]Thermodynamic properties of the liquid alloys of the Al-Ln binary systems

Ivanov M.I., Berezutsky V.V., Shevchenko M.O., Kudin V.G., Sudavtsova V.S.

1 Frantsevich Institute for Problems of Materials Science, Krzhizhanovsky str., 3, 03680, 2 Taras Shevchenko National University of Kyiv, Volodymyrska str. 64, 01033, Kyiv, Ukraine

e-mail: [email protected]

The thermochemical properties of alloys of the binary Al-Y(La, Eu, Yb) systems were determined using the calorimetry method. Integral mixing enthalpies of alloys of the Al-Y(La) systems were defined to reach a minimum -41 kJ/mol at xY = 0,4 and xLa = 0,36, and Al-Eu(Yb) ones – -23 kJ/mol at xEu(Yb) = 0,39. The activities of components of the Al-Y(Sc, La, Ce, Nd, Eu, Yb) alloys were calculated using the co-ordinates of the liquidus lines of these systems and the theory of ideal associated solutions (TIAS).

158


[P39]Thermodynamic Properties of Liquid Ti-Dy Alloys

M.O. Shevchenko1, Yu.V. Fartushna2, V.G. Kudin1, V.S. Sudavtsova2*, M.V. Bulanova2

1 Taras Shevchenko National University of Kyiv, Volodymyrska str. 64, 01033, Kyiv, Ukraine 2 Frantsevich Institute for Problems of Materials Science, Krzhizhanovsky str., 3, 03680,


Titanium alloys with rare earths (R) are interesting from both fundamental and practical points of view. Titanium affinity to the rare earth elements is low. As a result, Ti-R systems can be divided into two groups. The systems of the first group (R – from La to Gd and Y) show miscibility gap in a liquid, decreasing along the row. The systems of the second group (R – from Tb to Lu) are of a simple eutectic type. Both titanium and rare earths are chemically aggressive elements, so experimental study of Ti-R based systems is rather difficult. Especially this concerns thermodynamic properties of liquid alloys, which are unknown. Therefore, the goal of this work is to estimate thermodynamic properties of liquid Ti-Dy alloys on the basis of a phase diagram constructed by us, and using a methodology proposed by us. Resulting integral mixing enthalpy of Ti-Dy melts is positive and reaches a maximum of 7 kJ / mole at about 0.5<xDy<0.6. Activities of the components at 1800 K show essential positive deviations from the Raoult’s law, which are not enough, however, for a miscibility gap appearance. Integral mixing Gibbs energy is close to -3.5 kJ/mole at xDy=0.55, and excess Gibbs energy is about 7 kJ/mole. Excess mixing entropy can be considered about zero. Estimation of thermodynamic properties of liquid alloys in other Ti-R systems has shown that the integral mixing enthalpies of the melts are positive with maxima between 7 and 9 kJ/mole at about 0.4<xTi<0.5. Activities of the components also show large positive deviations from the Raoult’s law. Regular behavior of thermodynamic properties of liquid Ti-R melts is accounted for by a difference of atomic radii of the components (dimensional factor).

159


[P40]Thermodynamic Assessments of the [Co,Cr,Fe,Ni]-Pb Binary Systems

Vaajamo Iina, Taskinen Pekka

Aalto University School of Chemical Technology, Metallurgical thermodynamics and modelling research group, PL 16200, FI-00076 Aalto, Finland

Phase diagrams are basic information with high practical use e.g. in high temperature metal processing. With CALPHAD-method it is possible to assess critically the phase diagrams and build internally consistent databases with thermodynamic data of specific systems, while reducing expensive and time-consuming laboratory work. In this work the Pb-binaries of the system Co-Cr-Fe-Ni-Pb have been assessed with CALPHAD-method using experimental data from the literature and from the isothermal equilibration experiments reported in this study. The phase diagram and the excess Gibbs energy values of the solution phases, molten alloy and the solid solutions were calculated using the Redlich-Kister polynomials. The data was fitted by a least squares method using MTDATA software tool. The isothermal equilibration experiments were carried out in evacuated, argon filled and sealed quartz ampoules in a chamber furnace at about 1273-1573 K. A neck was made in the middle of the ampoule according to Fig. 1 in order to separate the metal saturated Pb melt and Pb saturated metal foil after equilibration by turning the ampoule 180º before quenching the ampoule into ice water. After quenching the ampoules were broke down and the compositions of saturated metals were analyzed with ICP and EPMA. The aim behind this paper is to build a database of lead based alloys as a part of the NPL-MIRO MTOX oxide database. The binaries are thus assessed or extrapolated to ternaries and higher order systems.

Figure 1 The quartz ampoule and the position of the samples inside the ampoule (e.g. Fe-Pb binary system).

160


[P41]Control on Low Melting Point Area In CaO-SiO2-Al2O3-MnO System

Wang Fuming1*, Wang Haitao1, Li Changrong2

1 School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, 100083, China

2 School of Materials Science and Engineering, University of Science and Technology Beijing, 100083, China

*e-mail address: [email protected]

The composition area of low melting point inclusions in CaO-SiO2-Al2O3-MnO system was calculated and analyzed by using thermodynamic software FactSage. The results show that the composition areas of low melting point inclusions increase at first, then decrease with alumina and calcium oxide contents increasing, respectively, as shown in Fig.1. However, it always increases with silica and manganese oxide contents rising, respectively. To obtain low melting point inclusions, alumina and silica contents should be approximately controlled to be 20%, 30%, respectively, the CaO content restricted to be 25%~30%, and calcium oxide content / silica content should be 0.8~1. Then iso-activity lines were drawn in CaO-SiO2-20%Al2O3-MnO diagram. Based on above data, the inclusions with good plasticity can be obtained in cord wire steel.

Keywords: inclusion; CaO-SiO2-Al2O3-MnO system; thermodynamic computation; composition control.

Fig.1 The effect of Al2O3 content on low melting area of CaO-SiO2-Al2O3-MnO system based on FactSage software.

Acknowledgements: Thanks to Thermfact and GTT-Technologies for the support of the FactSage software. The authors would like to acknowledge National Natural Science Foundation of China (No. 50874007).

161


[P42]Precipitation sequence of Al-Mg-Si-(Cu) alloys and its verification

by first-principles calculations

Xu Fang1, Kai Li1, Dongdong Zhao1, Yong Du1,2,*

1 State Key Lab of Powder Metallurgy, Central South University, Changsha, Hunan 410083, P.R China

2 Science Center for Phase Diagrams & Materials Design and Manufacture, Central South University, Changsha 410083, PR China


The whole precipitation sequences of two cast Al-Mg-Si alloys (containing no Cu or minor Cu) were investigated via X-ray diffraction, transmission electron microscopy and hardness examinations. The precipitation sequence of the Cu-free alloy can be expressed as: super-saturated solid solution (SSSS) → G.P. zones → pre-β″ → β″ → U2 + Si + β → Si + β, while that of the Cu-containing alloy is identified as: SSSS → G.P. zones → pre-β″ → β″ → Q′ + β + Si → Q + β + Si. The addition of Cu accelerates the microstructural evolution, induces the formation of Q′ and Q precipitates, and decreases the stability of β″ precipitates. The finite-temperature thermodynamic properties and stability of the metatable phases in the sequence have been computed by means of first-principles calculations, and the calculated results are consistent with the experimental observed sequence.

Acknowledgements: The financial support from the National Natural Science Foundation of China (Grant Nos. 50721003 and 50831007) is greatly acknowledged.

162


[P43]Phase relationship in the Tb-Fe-Cr ternary system at 600 °C

Yan Zhong1, Huai-Ying Zhou1,2,*, Chao-Hao Hu2, Shun-Kang Pan2

1 School of Materials Science and Engineering, Central South University, Changsha, Hunan 410083, PR China

2 School of Materials Science and Engineering, Guilin University of Electronic Technology, Guilin, Guangxi 541004, PR China

The phase relationships in the Tb-Fe-Cr ternary system at 600 °C have been investigated mainly by X-ray diffraction analysis and first-principles density functional theory calculations. The result shows that the isothermal section consists of 9 single-phase regions, 16 two-phase regions and 8 three-phase regions. The compound TbFe12-xCrx with the ThMn-type structure is found to have a broad solubility ranging from x = 1.4 to x = 2.6. The XRD patterns and total-energy calculations suggest that Tb2Fe17 crystallizes with the Th2Zn17-type rhombohedral structure under our experiment conditions. The solid solutions in this ternary system are formed by the substitution of Cr for Fe. The maximum solid solubilities of Cr in (Fe), Tb2Fe17, Tb6Fe23 and TbFe2 are about 17, 12.5, 3 and 7 at.% Cr, respectively.

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.00.0

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Fig. 1 The isothermal section of the Tb-Fe-Cr ternary system at 600 °C.

Acknowledgements: Y. Zhong and H.Y. Zhou are thankful for the financial support from the National Natural Science Foundation of China under Grant Nos. 50631040, 50961005 and 50901023. (E-mail: [email protected])

163


[P44]Experimental investigation and thermodynamic calculation

of the Mg-Ni-Zn System

Yingbiao Peng1, Yong Du1,2,*, Honghui Xu1, Peisheng Wang1, Chunsheng Sha1

1 State Key Lab of Powder Metallurgy, Central South University, Changsha, Hunan 410083, P.R China

2 Science Center for Phase Diagrams & Materials Design and Manufacture, Central South University, Changsha 410083, PR China


The isothermal section of the Mg-Ni-Zn system at 400°C was determined by using 19 alloys prepared with powder metallurgy method. The samples, which were annealed at 400°C for 40 days, were examined by means of optical microscopy, X-ray diffraction, and scanning electron microscopy with energy dispersive X-ray spectroscopy. The experimental results confirm the existence of a ternary compound τ reported in the literature. The composition range of this compound was determined to span from about 20 to 60 at.% Zn. Thermodynamic modeling of the Mg-Ni-Zn system was performed, and a set of self-consistent thermodynamic parameters in the Mg-Ni-Zn system was obtained by using the CALPHAD approach taking into account the present experimental data and the literature data. Good agreement between the calculated and measured phase diagrams indicates that the present thermodynamic description of this system is reasonable. Due to the high volatility of Zn, it is difficult to obtain the experimental information near the Zn-rich region. Future experiment is needed for this region.

Fig 1. Calculated isothermal section at 400 °C along with the present experimental data.

Acknowledgements The financial support from the National Natural Science Foundation of China (Grant Nos. 50971135, 50721003 and 50831007) is greatly acknowledged

164


[P45]Microstructure and mechanical properties of TiAlN/TiN

nano-multilayer coating

Li Chen1, 2, Yong Du1,*, Keke Chang1, Bing Yang1, Wei Pan2, Yingbiao Peng1


2 Dept. of Materials Science & Engineering, Tsinghua University, Beijing, 100084, China *E-mail: [email protected]

Multilayer Ti-Al-N coatings are used for various applications where hard, wear and oxidation resistant materials are needed. Here, we prepare TiAlN/TiN nano-multilayer coatings with modulation period of less than 20 nm in order to further improve the mechanical properties of Ti-Al-N coatings. Multilayer structure results in an increase in adhesion with substrates from ~72 N for Ti-Al-N coating to 98 N for TiAlN/TiN nano-multilayer. In addition, the interfaces of TiAlN/TiN nano-multilayer coating retard the outward diffusion of metal atoms (Al and Ti) and inward diffusion of O while exposing coating in air atmosphere at elevated temperatures, and thus improve its oxidation resistance. An improved machining performance in both continuous cutting and milling is obtained by TiAlN/TiN nano-multilayer coated inserts, which can be attributed to the combined effects of higher adhesion with substrates and better oxidation resistance.

Acknowledgements The financial support from National Natural Science Foundation for Youth of China (Grant No.51001120) and the postdoctoral foundation of China (Grant No. 20100470060) is greatly acknowledged.

165


[P46]A thermodynamic modeling of the Pd−Ti system

Zhenmin Du, Cuiping Guo, Mei Li, Changrong Li

Department of Materials Science and Engineering, University of Science and Technology Beijing

The phase equilibria and thermodynamic properties of the Pd−Ti system were optimized using the CALPHAD (CALculation of PHAse Diagram) technique. The solution phases, liquid, bcc, fcc, and hcp were modeled with the substitutional-solution model. Both the compounds Pd2Ti and PdTi2 having a tetragonal MoSi2-type structure were treated as one phase with the formula PdTi(Pd, Ti) by a three-sublattice model with Pd on the first sublattice, Ti on the second and Pd and Ti on the third one, respectively. The intermetallic compounds Pd3Ti, Pd3Ti2, and PdTi3 were treated as stoichiometric compounds. The intermetallic compound αPdTi, which had a homogeneity range, was treated as the formula (Pd,Ti)(Pd,Ti) by a two-sublattice model. A two-sublattice model (Pd,Ti)0.5(Pd,Ti)0.5 was applied to describe the compound βPdTi in order to cope with the second-order transition between βPdTi with CsCl-type structure (B2) and body-centered cubic solution (A2) in the Pd−Ti system. A set of self-consistent thermodynamic parameters was obtained. This work was supported by National Natural Science Foundation of China (NSFC) (Grant Nos. 50971027, 50934011).

Key words: Pd−Ti phase diagram; thermodynamic properties; order−disorder transition; CALPHAD technique.

166


[P47]Thermodynamic description of the Mg-Sn-Y system

Zhenmin Du, Dongxian Lü, Cuiping Guo, Changrong Li

Department of Materials Science and Engineering, University of Science and Technology Beijing, Beijing

The Sn-Y and Mg-Sn-Y systems were assessed by means of the CALPHAD technique on the basis of available experimental information. In the Sn-Y binary system, the solution phases (liquid, bcc, bct and hcp) are described by the substitutional solution model, Sn3Y5 intermetallic compound, which has a homogeneity range, was treated by a three-sublattice model as the formula (Sn,Y)3(Y, Sn)2Y3 in accordance with the site occupancies, and the others compounds, Sn4Y5, Sn10Y11, Sn2Y, Sn5Y2 and Sn3Y were treated as stoichiometric compounds. Combined with the thermodynamic parameters of the Mg-Sn and Mg-Y binary systems in literature, the thermodynamic modeling of the Mg-Sn-Y ternary system was performed. The liquid phase is described by the associated solution model with an associate Mg2Sn, while the solid solution phases, bcc, hcp, are modeled by the substitutional solution model. The compound Sn3Y5 in the Sn-Y system was treated as (Sn,Y, Mg)3(Y, Sn, Mg)2Y3 in the Mg-Sn-Y system. The MgSnY ternary compound was treated as stoichiometric compound on the basis of the experimental information. A set of self-consistent thermodynamic parameters of the Mg-Sn-Y system was obtained.

This work was supported by National Natural Science Foundation of China (NSFC) (Grant Nos. 50731002, 50801004).

Key words: Mg-Sn-Y system; CALPHAD technique; Thermodynamic parameters.

167


[P48]Thermodynamic re-assessment of the Ni–Sn system

Jinming Liu, Cuiping Guo, Changrong Li, Zhenmin Du*

Department of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, PR China

*e-mail address: [email protected]

The Ni–Sn system was critically re-assessed by means of the CALPHAD technique. The excess Gibbs energy of the solution phases (liquid, fcc and bct) were modeled with the Redlich-Kister equation. Five intermetallic compounds, Ni3Sn_HT (which is stable at high temperature), Ni3Sn_LT (which is stable at low temperature), Ni3Sn2_HT, Ni3Sn2_LT and Ni3Sn4 in the Ni–Sn system were treated as the formula (Ni,Sn)0.25(Ni,Sn)0.25(Ni)0.5, (Ni,Sn)0.75(Ni,Sn)0.25, (Ni)0.3333(Ni,Sn)0.3334(Sn)0.3333, (Sn)0.2(Ni,Sn)0.4(Ni)0.4, and (Ni)0.25(Ni,Sn)0.25(Ni)0.5, respectively. A set of self-consistent thermodynamic parameters of the Ni–Sn system was obtained. The calculated Ni–Sn phase diagram and enthalpies of mixing of liquid at 1550 K and comparison with the experimental data, as shown in Figs. 1 and 2.

Keywords: Ni–Sn phase diagram; Thermodynamic assessment; Thermodynamic properties; CALPHAD technique.

Fig. 1 Calculated Ni-Sn phase diagram by the present thermodynamic description with

experimental data measured by Schmetterer et al. [11].

Fig. 2 Calculated enthalpies of mixing of liquid at 1550 K in the Ni-Sn system and comparison with the experimental data [36-38]. The reference states

of elements are liquid for Ni and Sn.

This work was supported by National Natural Science Foundation of China (NSFC) (Grant Nos. 50801004, 50931002).

168


[P49]Predicting diffusion coefficients in magnetic phases by

first-principles methodologies

Zi-Kui Liu, Chelsey Zacherl, ShunLi Shang, Yi Wang

The Pennsylvania State University

Predicting self-diffusion and impurity-diffusion coefficients by computational methods is an attractive alternative to lengthy and costly experimental techniques. Methods for computational calculation of cubic and hexagonal systems have been developed and are based on parameter free first-principles calculations. However, a method for calculation diffusion coefficients of magnetic systems without an empirical model for representing the magnetic transition has not been discovered. As a baseline, diffusion coefficients in antiferromagnetic Cr are predicted based on current first- principles techniques. Cluster expansion, Debye model, and phonon first-principles approaches are used in the present work to examine and represent the properties of magnetic Ni at its ferromagnetic to paramagnetic transition. The work being presented focuses on progress made toward the development of an entirely first-principles prediction of self-diffusion and impurity diffusion in magnetic Ni.

Key words: Magnetic phases.

169



Database development

170


[P50]The Thermodynamics of Aluminum Nitride Precipitation in Steels Revisited

A. Costa e Silva1, M. A. da Cunha2, L.N.A. Vieira2, F. Rizzo3

1EEIMVR-UFF 2Aperam (ArcelorMittal)

3DCMM-PUC RJ

In previous work [1] the possibilities and limitations of the application of calculations in the Al-Fe-N system to describe the precipitation of AlN mostly in austenite (FCC) and in during the solidification were discussed. Assessed values in computational thermodynamic databases were compared to “classical” solubility products and experimental data in the usual ranges of austenite thermomechanical processing. The results were also used to evaluate the possibility of “rock candy” fracture. Presently, the precipitation of AlN in ferrite (BCC) is discussed. This is specially relevant for two reasons: (a) some classes of deep drawing steels have their processing designed to favor the precipitation of this nitride concurrently with the annealing treatment, when the steel is mostly ferritic and (b) some silicon alloyed electric steels make extensive use of the precipitation of this nitride at relatively high temperatures, when these steels can have significant fractions of BCC in their microstructure. The precise knowledge of the precipitation-dissolution behavior of AlN in these two classes of steels is of great importance to their correct processing. In this work, the information available on the solubility of AlN in BCC is compiled and compared, considering, as much as possible, the interaction with other relevant solutes, mostly silicon, carbon and manganese. Some discrepancies are identified and some possible reasons for these are indicated. Furthermore, the impact of the use of different sources of data on steel processing development is discussed and the need for further studies highlighted.

Key words: Thermodynamics.

[1] A. Costa e Silva, F. Rizzo and J. G. Speer, A Study of the Thermodynamics of Aluminum Nitride Precipitation in Steels and Ferrous Alloys, XXXI CALPHAD, Stockholm, Sweden, May 2002.

171


[P51]Thermodynamics of flux behavior in steel welding with focus on

hydrogen in steel

A. Costa e Silva1, A.Q. Bracarense2, E.C.P. Pessoa2, M. Monteiro3, R. Avillez3, F. Rizzo3, V.R.Santos3

1EEIMVR-UFF 2UFMG

3DCMM-PUC RJ

In previous work the fundamentals of hydrogen absorption from moisture in liquid steel were review and applied to provide a preliminary interpretation of results of underwater welding with different electrode coatings [1]. Hydrogen can cause several problems in steel such as embrittlement, cracks (sometimes called “flakes” in the steel industry), pores and bubbles. The extremely high mobility of hydrogen in iron aggravates these problems. A large portion of the knowledge about the thermodynamic of hydrogen in steels and slags is well established. In this work, the basic aspects of the thermodynamics of hydrogen in steel entry in the liquid state are reviewed: the importance of oxygen activity and iron content in slag and how alloying elements partition between slag and melt affect these variables is discussed. The effect of the atmosphere above the liquid steel is also discussed. The application of this knowledge to welding, in special underwater welds is presented: results of hydrogen absorption in welds using different electrode coatings are compared with computational thermodynamic calculations, in which an attempt to calculate the slag-metal partition of the different elements and of oxygen is made. The results are discussed and some guidelines for slag selection, purely from the thermodynamic point of view, are proposed. The lack of reliably assessed data for some of the oxides in the slag requires the use of preliminary assessed coefficients, which might limit the accuracy of the predictions. The most relevant compounds for which data is missing are listed, in order to initiate a project to assess their Gibbs energy in a slag described by the Kapoor-Frohberg-Gaye model.

Key words: Thermodynamics.

[1] A. Costa e Silva, A.Q. Bracarense, E.C.P. Pessoa, M. Monteiro, R. Avillez, F. Rizzo and V.R.Santos, Thermodynamics of hydrogen in steel - application to underwater welding XXXVIII CALPHAD, Prague, Czech Republic, May 2009.

172


[P52]TCAL1: A new thermodynamic database for Aluminium alloys

A. Markström1, Y. Du2, S.H. Liu2, L.J. Zhang2, L. Kjellqvist1, J. Bratberg1, A. Engström1

1 Thermo-Calc Software AB, Norra Stationsgatan 93 (Plan 5), 113 64 Stockholm, Sweden 2 State Key Laboratory of Powder Metallurgy, Central South University,

Changsha, Hunan, 410083, P. R. China

Thermodynamic databases developed using the CALPHAD method have been successfully applied to the modelling and simulation of Al based alloys for more than fifteen years. Such databases when combined with suitable software can be used for accelerating alloy design as well as improving understanding of existing alloys in terms of their processing and in-service behaviour. Additionally, such databases are also essential to the modelling of microstructural evolution using methods such as phase field codes and steady state approaches. A new thermodynamic database has been developed for Al-base alloys based on the critical evaluation, using the CALPHAD method, of all the constituent binary systems across their full range of composition and 59 ternaries, 15 quaternaries and 1 quinary. This new database contains all the important Al-based alloy phases within a 26-element framework [Al Cu Fe Mg Mn Ni Si Zn B C Cr Ge Sn Sr Ti V Zr Ag Ca H Hf K La Li Na Sc] and in total 345 solution and intermetallic phases are included in this database. Also of note is that the ordered and disordered bcc (A2 and B2) and fcc (A1 and L12/γ´) phase have been modelled with a two sub-lattice model using a single Gibbs energy curve, and this type of description is of particular importance to be able to predict second order transformations between A2 and B2. Calculations on different kind of commercial alloys show a very good accuracy of the database, both when it comes to prediction of phases that are formed and the temperature for formation. Solidification simulations are shown for various kinds of commercial Al-alloys and are compared with experimental data.

173


[P53]A thermodynamic database of phase diagram in alloy systems including rare

earth elements

C.P. Wang, S.X. Gan, X.J. Liu

Xiamen University, China

The rare earth elements have good combination of magnetic, optical, electrical and thermal characteristics, and have been widely used to prepare new materials. As the map for materials design, the phase diagram can give an important direction for development of the rare earth alloy materials. Thus, development of the thermodynamic database of the phase equilibria in the rare earth alloy systems is important and necessary. In this work, the thermodynamic assessments of phase diagrams in the binary and ternary systems with rare earth elements have been carried out by using CALPHAD (Calculation of Phase Diagrams) method on the basis of the experimental data including thermodynamic properties and phase equilibria. Gibbs free energies of the solution phases were described by subregular solution model with the Redlich-Kister equation, and those of the intermetallic compounds and gas phase were respectively described by sublattice model and ideal gas model. A consistent set of thermodynamic parameters have been derived for describing the Gibbs free energies of each solution phase and intermetallic compound. The calculated phase diagrams and thermodynamic properties are in good agreement with the experimental data. The thermodynamic database of alloy systems with rare earth elements has been developed, which will provide important information including phase diagrams and various thermodynamic properties for development of alloy materials with rare earth elements.

Key words: Thermodynamic database; Rare earth alloy; CALPHAD.

174


[P54]Thermodynamic Modeling of the Y2O3-Nb2O5 System

Nara M. Guimarães1, Danieli A. P. Reis1, Carlos de Moura Neto1, Gilberto C. Coelho2,3, Daniel S. de Almeida4

1Instituto Tecnológico de Aeronáutica –ITA, São José dos Campos, SP, Brazil 2Escola de Engenharia de Lorena, Universidade de São Paulo, Lorena, SP, Brazil

3Centro Universitário de Volta Redonda – UniFOA/MEMAT, Volta Redonda, RJ, Brazil 4Departamento de Ciência e Tecnologia Aeroespacial – DCTA, São José dos Campos, SP, Brazil

A great effort has been done by the scientific community to increase efficiency and decrease greenhouse gas emissions of energy generation equipments. This has lead materials scientists and engineers to develop new substrate and coating materials. Oxide coatings are commonly used to protect Ni-based superalloys against oxidation and hot-corrosion. Thermal barrier coatings (TBCs) are used on top of other coating systems in order to lower the metal surface temperature and increase its lifetime. TBCs are usually composed by yttria-stabilized zirconia (YSZ) ceramic materials. Co-doping with rare earth oxides increases the thermal insulation efficiency [1,2]. Hot-corrosion resistance has been improved by Ta2O5 additions [3]. A thermodynamic database specialized in TBC systems is commercially available, namely STBC1 – SGTE Thermal Barrier Coating Database [4], containing however information only for the ZrO2-Al2O3-Gd2O3-Y2O3 system. The present work aims at contributing to the development of thermal barrier coating databases through the modeling of the Y2O3-Nb2O5 system. All information available in the literature together with our own experimental results such as phase quantification and transition temperatures have been used as a basis for the thermodynamic modeling. The calculated phase diagram reproduces well the available experimental data. However, this result has still a preliminary character because of the lack of thermochemical information on the system.

Key words: Y2O3-Nb2O5 system, Thermodynamic modeling.

[1] Nicholls, J.R. Advances in coating design for high-performance gas turbines. MRS Bulletin, September/2003. [2] Fabrichnaya, O.; Wang, CH.; Zinkevich, M.; Levi, C.G.; Aldinger, F. Phase equilibria and thermodynamic properties of the ZrO2-GdO1,5-YO1,5 system. Journal of Phase Equilibria and Diffusion, v.26, n.6, 591-604, 2005. [3] Pitek, F.M. A study of the zirconia-yttria-tantala system as a potencial thermal barrier oxide. Dissertation of Doctor degree, University of California, 2006. [4] Thermo-Calc Database Guide. Foundation of Computational Thermodynamics – Stockholm, Sweden.

175


[P55]Thermodynamic assessment of CsBr-LnBr3 system (Ln = La, Ce, Tb)

Weiping Gong1, Yue Wu1, Marcelle Gaune-Escard2

1State Key Laboratory of Powder Metallurgy, Central South University 2Polytech Marseille, IUSTI

Lanthanide halides and their mixtures with alkali metal halides play a significant role in a number of industrial applications largely based on molten salt technologies, many still under development. Their thermodynamic and transport properties can provide basic information for process development and optimization. However these data are scarce and not easily accessible in literature. Accordingly, intensive efforts are being made at an international level both in R&D aspects and also in database development. Based on the experimental phase diagram and thermodynamic data, thermodynamic assessment on the CsBr-LnBr3 (Ln = La, Ce, Tb) mixtures were performed using the CALPHAD method. A two sub-lattice ionic solution model, (Cs+)P:(Br-, LnBr6-3, LnBr3)Q, was used to describe the liquid phase. The phase diagrams, thermodynamic properties and the general features of the CsBr-LnBr3 mixtures (Ln= La, Ce, Tb) were obtained reliably. And a critical discussion was given.

Key words: Phase diagrams, Lanthanide, Rare Earth, Halides, Thermodynamics, Associate Model.

176



Diffusion and phase transformation modeling

177


[P56]Calculation of different Co diffusion kinetics along alpha-Zr grain boundaries at

power reactor temperatures under normal conditions

Carolina Corvalan1, Manuel Iribarren1, Julio Sola2

1CNEA- Argentine Atomic Energy Comission - Materials Department/UNTreF- Tres de Febrero University, Buenos Aires, Argentina,

2UNTreF- Tres de Febrero University, Buenos Aires, Argentina

Zirconium is the base material for nuclear devices. During normal operation conditions this structural material presents an important density of grain or interphase boundaries. The atomic transport along these short-circuits diffusion is several orders of magnitude faster than in the crystal. At low temperatures, the diffusion processes are often not properly considered. In fact, even when bulk diffusion can be neglected the atomic displacement along grain boundaries is important and the whole diffusion processes becomes relevant. The Co presents a fast diffusion in the bulk of Zr based alloys [1] and recent experiments show his ultra-fast diffusion along alpha-Zr grain boundaries [2]. Particularly for the Co60 radioisopes production for the nuclear medicine the diffusion process of this element plays a key role in order to guarantee the security conditions. In this work the simulation results of Co diffusion in Zr grain boundaries in different Harrison kinetics[3] are showed in the [373-573] K temperature range at different times. The simulations have been performed with DICTRA software. The results are discussed in comparison to previous experimental data. Finally the segregation factor and the validity of the different kinetic regimes are evaluated.

Key words: Diffusion kinetics, zirconium,DICTRA simulations.

[1] G.V. Kidson: Phil. Mag. Vol. A44 (1981), p. 341. [2] C. Corvalan Moya et al. Defect and Diffusion Forum Vols. 283-286 (2009) p. 669. [3] L.G. Harrison: Trans. Faraday Soc. Vol. 57 (1961), p. 1191.

178


[P57]Numerical simulation of precipitate evolution in ferritic-martensitic

power plant steels

K.C. Hari Kumar, V.B. Rajkumar, B.S. Srinivas Prasad

Department of Metallurgical and Materials Engineering, Indian Institute of Technology Madras - Chennai 600 036, India

Knowledge about the nature of precipitates present and their evolution with respect to time is found to be very critical to increase the operating temperature in power plant steels [1]. Evolution of most important precipitates in P91, RAFM and E911 steels are studied using the equilibrium thermodynamics tool Thermo-Calc and the kinetic simulation tool MatCalc. We have used an ingeniously developed thermodynamic database for steels and a modified version of public domain mobility data base to achieve this. Variation of precipitate mean radii and phase fractions of M23C6, MX, Laves, Z phase, M7C3 precipitates with time were simulated. Effect of certain alloying elements like Molybdenum, Tantalum etc., on the precipitation phenomenon in P91, RAFM and E911 steels is studied. Simulations are carried out for different heat treatment schedules and the results are compared with the experimental data from literature.

Key words: steels, precipitation, simulation, kinetics.

[1] F. Abe, Strengthening mechanisms in steel for creep and creep rupture, in: F.Abe, T.U. Kern, R. Viswanathan (Eds.), Creep-resistant Steels, Woodhead Publishing Ltd., Cambridge, 2008, pp. 279-304.

179


[P58]Microstructure Evolution by Solid-state Reactive Diffusion

in the (Ni−Cr)/Sn System

M. Kajihara, K. Motojima, T. Asano

Department of Materials Science and Engineering, Tokyo Institute of Technology, Japan

Owing to high electrical conductivity, Cu-base alloys are widely used as conductor materials in the electronics industry. If the Cu-base conductor is interconnected with a Sn-base solder, Cu6Sn5 and Cu3Sn are formed at the interconnection between the conductor and the solder during soldering and then gradually grow during energization heating at solid-state temperatures. The Cu−Sn compounds are brittle and possess high electrical resistivities. Thus, the growth of the compounds deteriorates the mechanical and electrical properties of the interconnection. To inhibit the formation of the compounds, the Cu-base conductor is usually plated with a Ni layer. The addition of Cr into the Ni layer improves corrosion resistance and may influence the compound formation. To examine this influence, the kinetics of the solid-state reactive diffusion in the (Ni−Cr)/Sn system was experimentally observed by a metallographical technique. In the experiment, Sn/(Ni−Cr)/Sn diffusion couples with Cr concentrations of 5.0, 11.7, 15.0, 23.2 and 28.2 at.% were isothermally annealed at temperatures of 453−473 K for various times up to 1200 h. During annealing, a multiphase layer consisting of Ni3Sn4, CrSn2 and Sn is formed at the initial (Ni−Cr)/Sn interface in the diffusion couple. This multiphase layer is merely called the intermetallic layer. Diffusion paths at 473 K for various diffusion couples are shown in Fig. 1. On the other hand, Fig. 2 indicates the result of 473 K for the mean thickness l of the intermetallic layer versus the annealing time t. As can be seen, l is proportional to a power function of t, and the exponent n of the power function takes values of 0.60−0.75. This means that the interface reaction as well as the interdiffusion contributes to the rate-controlling process for the growth of the intermetallic layer. At the experimental annealing times, the overall growth rate of the intermetallic layer reaches the maximum value at a Cr concentration of 12 at.%.

Fig. 1 Diffusion paths at 473 K. Fig. 2 The dependence of l on t at 473 K.

180


[P59]Phase Transformations In The Annealing Of Sm-Co-Fe-Cu-Zr Magnets

Marcos Flavio de Campos1, Jose Adilson de Castro1, Sergio Antonio Romero2, Marcelo F Moreira3, Fernando J G Landgraf4

1Universidade Federal Fluminense, 2IFUSP Universidade de São Paulo, 3Instituto de Pesquisas Tecnologicas,

4Instituto de Pesquisas Tecnologicas / Universidade de Sao Paulo

The processing of Sm2Co17 type magnets - in fact (SmZr)2(CoFeCu)17 - includes a complex heat treatment, with the following sequence (steps 1-4): 1) solubilization at 1200 °C (4h), 2) quenching, 3) precipitation heat treatment at 800-850 °C (or 820 °C) for several hours (7h) 4) slow colling, from 820 °C to 400 °C, at 1 °C/min This process involves several phase transformations, leading to a nanostructure, which is responsible for the excellent magnetic properties of these alloys [1,2]. In the present An isotropic magnet with composition Sm0.104Co0.60Fe0.195Cu0.072Zr0.02 was submitted to the heat treatment described above. The nanoscale microstructure was evaluated with FEG SEM (Field Emission Gun Scanning Electron Microscope) and with Synchrotron X-Ray Diffraction (XRD), used for Rietveld Analysis. At the step 1, the only phase present is disordered 2:17 R (rhombohedral, 166 structure), which may present different chemical compositions At the step 3, temperature around 820 °C, the following phase transformation takes place, 2:17R (disordered) --> 1:3 + 1:5 + 2:17R (ordered). There is a formation of nanoscale structure with Sm2(Co,Fe)17 cell phase (rhombohedral 166 structure), Sm(CoCu)5 cell boundary phase (hexagonal 191 structure) and the lamellae phase, (ZrSm)1(CoFeCu)3. The 1:3 phase has been described as Rhombohedral Sm1Zr2Co9, a stable phase in the ternarium Sm-Zr-Co It is presented a diffusion model (based on the Finite volume method). This model takes into account copper and samarium diffusion. The model is able to describe the kinetics of the phase transformations, which results in the excellent magnetic properties found in these alloys. Acknowledgements FAPERJ CNPq.

Key words: SmCoFeCuZr, diffusion, phase transformations, heat treatment.

[1] M.M. Corte-Real, M.F. de Campos,Y. Zhang, G.C. Hadjipanayis and J.F. Liu. Phys. Stat.Sol.(a) Vol. 193 (2002), p. 302. [2] S. A. Romero, M. F. de Campos, H. Rechenberg and F. P. Missell: Journal of Magnetism and Magnetic Materials Vol. 320 (2008).

181


[P60]Kinetic Simulation of Carbon migration During Quenching and Partitioning

(Q and P) Treatment of Steels

S. Sankaran1, N. Maheswari1, V.B. Rajkumar1, S.G. Chowdhary2, K.C. Hari Kumar1

1Department of Metallurgical and Materials Engineering, Indian Institute of Technology Madras - Chennai 600 036, India 2National Metallurgical Laboratory, Jamshedpur 831007, India

Quenching and partitioning is a novel heat treatment process which can be used to generate steels with optimum strength and ductility. The process involves quenching the steel below the martensite-start temperature (MS), followed by a partitioning treatment (reheating slightly below MS) to enrich the remaining austenite with carbon, thereby stabilizing it to room temperature. During this process the competing reactions, mainly carbide precipitation, can be suppressed by appropriate alloying with Si and Al [1-3]. Desirable alloy compositions selected for the present simulation are in the range of C=0.2-0.3, Si=0.4-1.6, Mn=1.2-1.75, Al=1-1.6. Thermodynamic and kinetic calculations were performed using MatCalc and Thermo-Calc software. The partitioning of carbon from martensite (here considered as supersaturated BCC matrix) to austenite (FCC matrix) has been modeled using the indigenously developed thermodynamic database combining it with an open source mobility database. A carbon diffusion profile has been calculated and it will be useful to decide the proper partitioning temperature and time to obtain the desired microstructure.

Key words: Heat treatment, Steels, Kinetics, Simulation.

[1] A.J. Clarke, J.G. Speer, M.K. Miller, R.E. Hackenberg, D.V. Edmonds, D.K.Matlock, F.C. Rizzo, K.D. Clarke, E. De Moor, Acta Mater. 56 (2008) 16-22. [2] J.G. Speer, D.V. Edmonds, F.C. Rizzo, D.K. Matlock, Current Opinion in Solid State and Materials Science. 8 (2004) 219-237.

182



Experimental measurements

183


[P61]Experimental determination of phase equilibria in the iron-rich side

of the Cu-Fe-Ni system between 873 K and 1273 K

Annie Antoni-Zdziobek, Sabine Lay, Coraline Crozet

SIMAP GrenobleINP

Although the Cu-Fe-Ni system has been the subject of several investigations, published information of the phase diagram of this system is relatively incomplete, particularly in the Fe-rich side of the system. Only few data concerning the crystallographic nature of phases have been reported. A new experimental study has been carried out to contribute to the knowledge of phase equilibria of this system. Two key Cu/Fe/Ni diffusion multiple and twenty-three decisive alloys have been prepared, directed by a critical evaluation of the data available in the literature and by computer calculations. A combination of EPMA and metallography is used to determine accurately the phase boundaries. XRD is used on equilibrated alloys to identify the crystallographic nature of the phases. It is shown that it is not possible to retain the high-temperature phase g(fcc) to room temperature even by a fast quench and that g(fcc) to a(bcc) partitionless transition takes place. However, heating/cooling experiments which could avoid the possibility of a phase change during quenching are not suitable: it is shown by dilatometry that metastable structures are produced even during very slow cooling process as 0.03°C/s. Using diffusion multiple and equilibrated alloys, tie-lines of the g1/g2 (where g1 is enriched in Fe and Ni and g2 is enriched in Cu) phase equilibria were obtained at 1073 K and 1273K. Tie-lines of the aFe/g1 and aFe/g2 phase equilibria were obtained at 1073 K. The three phase field aFe + g1 + g2 was determined at 873 K. The calculated miscibility gap is less extended for high Ni content than indicated by the experimental values. On the contrary, Fe solubility in the g1 phase is higher than the calculated values. It appeared that phase equilibria in the Cu-rich corner were dependant on the method for the equilibrated alloys preparation. Therefore a comparison of the different methods used in the litterature, cast or sintered alloy, is given and our findings are discussed.

Key words: Cu-Fe-Ni, diffusion multiple, equilibrated alloys, partitionless transition g(fcc) to a(bcc).

184


[P62]Experimental Investigation and Thermodynamic Assessment

of the V-Si-B System

Carlos Angelo Nunes1, Gilberto Carvalho Coelho1,2,Belmira Benedita de Lima1, Tales Ferreira Villela1,3, Nicolas David4, Jean Marc Fiorani4, Michel Vilasi4

1Universidade de São Paulo (USP), Escola de Engenharia de Lorena (EEL), Pólo Urbo-Industrial Gleba AI-6, Caixa Postal 116, 12600-970, Lorena, São Paulo, Brazil

2Centro Universitário de Volta Redonda (UniFoa), Núcleo de Pesquisa, Campus Três Poços, Av. Paulo Erlei Alves Abrantes, 1325, Bairro Três Poços, 27240-560, Volta Redonda, Rio de Janeiro, Brazil 3Universidade Federal Fluminense (UFF), Escola de Engenharia Industrial Metalúrgica de Volta Redonda,

Av. dos Trabalhadores 420, 27260-740 Volta Redonda, Rio de Janeiro, Brazil 4Université Henri Poincaré Nancy 1, Institut Jean Lamour, Départment Chimie et Physique des Solides et

des Surfaces, UMR7198 CNRS, Boulevard des Aiguillettes, BP 70239, 54506, Vandoeuvre-lès-Nancy, France

Based on the technological interest of Me-Si-B for structural, high-temperature applications, this investigation focused initially on the experimental evaluation of the V-Si-B system in the V-VB-VSi2 region. It was possible to establish an isothermal section at 1600oC and a liquidus projection. The isothermal section data indicated a negligible solubility of B in the V3Si and V5Si3 (T1) and V6Si5 phases as well as of Si in V3B2 and VB phases. Two ternary phases presenting the structures known as T2 (Cr5B3-prototype) and D88 (Mn5Si3-prototype) were observed in both as-cast and heat-treated samples. With respect to the liquidus projection data, nine regions of primary solidification were identified (Vss, V3Si, T2, V5Si3, V6Si5, D88, VSi2, VB) and eight invariant four-phase reactions. From these experimental and literature data (T-x data; Cp, enthalpy of formation), the thermodynamic optimization of the Gibbs energy functions of the phases was carried out using the Parrot Module of Thermo-Calc. In general, a good agreement between the experimental and calculated data was achieved.

Keywords: V-Si-B System, Phase Diagram, Liquidus Projection, Isothermal Section, Thermodynamic Modeling.

185


[P63]Casting and characterization of Ni-, Fe(Ni)- and Fe-based 30%Cr-containing

alloys strengthened by TaC; comparison with thermodynamic calculations

C. Vébert,1 Y. Hamini,1 L. Héricher,1 S. Michon,1 L. Aranda,2 P. Berthod2

1University Henri Poincaré, Faculty of Sciences and Technologies 2Institut Jean Lamour, University Henri Poincaré, Faculty of Sciences and Technologies

Tantalum carbides are of a great interest for reinforcing refractory alloys since they are among the most stable ones at high temperatures. It is why they are often used in cast cobalt-based superalloys, alone or in addition to other types of carbides less stable (e.g. chromium carbides), to efficiently strengthen these ones in service for resisting creep deformation under applied mechanical stresses. Such TaC carbides are less common in the microstructures of nickel-based or iron-based alloys, which can be also considered for high temperature applications. TaC carbides are potential strengthening particles in such alloys when they need containing chromium for resisting hot corrosion instead of aluminum. Three nickel-based alloys, three {iron+nickel }-alloys and three iron-based alloys, all containing 30wt.%Cr as well as carbon and tantalum quantities allowing them to possibly develop interdendritic TaC-carbides are solidification, were elaborated by foundry under inert atmospheres. They were metallographically examined in the as-cast condition and in three heat-treated states (at 1000, 1100 and 1200°C). Their melting temperature ranges were also specified by DTA/DSC measurements. All these experimental data were thereafter compared to results of thermodynamic calculations performed with Thermo-Calc. If some TaC carbides were obtained in the nickel-based alloys after solidification in the Ni-based alloys (mixed with chromium carbides), these ones tended to disappear during the subsequent exposures to high temperature. In contrast, TaC carbides precipitated in much greater quantities during solidification in the (Fe, Ni)-based and Fe-based alloys and they remained stable during the heat-treatments at high temperatures. These observations, as well as the measured solidus and liquidus temperatures were not always in good agreement with thermodynamic calculations, revealing that the used home-made database needs to be improved.

Key words: Ni-based alloys, Ferritic Fe-based alloys, Austenitic FeNi-based alloys, TaC carbides, Thermodynamic calculations.

[1] S. Michon, P. Berthod, L. Aranda, C. Rapin, R. Podor, P. Steinmetz, Calphad, 2003, 27(3), 289-294. [2] P. Berthod, L. Aranda, C. Vébert, S. Michon, Calphad, 2004, 28, 159-166. [3] P. Berthod, Y. Hamini, L. Aranda, L. Héricher, Calphad, 2007, 31, 351-360. [4] P. Berthod, Y. Hamini, L. Héricher, L. Aranda, Calphad, 2007, 31, 361-369.

186


[P64]Experimental investigation and thermodynamic modeling of the Zn-V-X

(X=Sn, Ti, Si) ternary systems

Changjun Wu1, Xuping Su2, Jianhua Wang2, Ya Liu2, Haoping Peng1, Hao Tu2

1Key Laboratory of Materials Design and Preparation Technology of Hunan Province, Xiangtan University, Hunan, P.R. China,

2Key Laboratory of Advanced Metal Materials of Changzhou City, Changzhou University, Jiangsu, P.R. China

The Zn-V-Sn and Zn-V-Ti alloys can well suppress high Si-reactivity during galvanizing. Investigation of the Zn-V-Si system helps to understand the effect of V on galvanizing Si-containing steel. To build a Zn-based alloys thermodynamic database, the phase equilibria of these ternary systems, including isothermal section 450°C and 600°C, were experimentally investigated by means of X-ray powder diffraction (XRD), differential thermal analysis (DTA) and scanning electron microscopy coupled with energy/wave dispersive spectroscopy (SEM-EDS/WDS). In addition, these systems were thermodynamic assessed in the present work. Two ternary compounds, V13Sn23Zn64 and V11Sn13Zn76, which have narrow composition range, were found in the Zn-Sn-V system. While no ternary compound was found in the Zn-V-Ti and Zn-V-Si systems. The experimental results indicated that neither Si nor Sn can dissolve into VZn3 and V4Zn5. However, TiZn3 and VZn3 form a continuous solid solution. And the solubility of Zn in VSn2, V3Sn, VSi2, V5Si3 and V3Si are about 2.5at.%, 4.8at.%, 1at.%, 2.6at.% and 2.1 at.%, respectively. Based on present results and available information, these systems were thermodynamically assessed. Acknowledgement: The financial support from Qinlan project and National Natural Science Foundation of China (Nos. 50971110 and 50971111) are greatly acknowledged.

Key words: Zn-V-X (X=Sn, Ti, Si), CALPHAD, galvanizing, phase diagram.

187


[P65]Experimental Studies and Re-assessment of the Quasi-binary Systems containing

the Sulfates of Sodium, Potassium, and Calcium by Differential Thermal Analysis and X-Ray Diffraction

D. Kobertz and M. Müller

Forschungszentrum Jülich, IEK-2, D-52425 Jülich, Germany, email: [email protected]

The combustion of lignite containing high amounts of sulfur, calcium, potassium, and sodium induces the formation of sulfatic depositions and corrosion related processes on refractory metal and ceramic material. These depositions diminish the heat conductance and their spalling leads to damages in the power plant. The mechanisms for the formation of these conglomerations are initiated by low-melting or related to adhesive sulfatic phases. Limitation of fossil fuel resources requires an increase of the efficiency of power plants by using combined cycle power systems. The pressurized pulverized coal combustion (PPCC) combined cycle is a coal fired combined cycle concept which is able to achieve efficiencies in excess of 53%. The direct use of the hot flue gas for driving a gas turbine requires a hot gas cleanup to achieve corrosion prevention of the turbine blading. Hot corrosion on turbine blading is initiated by deposition or condensation of corrosive species like alkali sulfates and dependent on concentrations of alkalis in the hot flue gas. Type I hot corrosion is caused by the formation of liquid Na2SO4 above its melting point (884 °C). Type II hot corrosion is caused by the formation of an eutectic melt of NiSO4 and Na2SO4 above 671 °C. NiSO4 itself is formed by the reaction of the oxide scale of Ni base alloys in blading with SO3 in dependence of the SO3 partial pressure in the hot flue gas. The motivation of our studies is to understand the aforementioned alkali sulfate related processes under applied conditions and accrued phases. Multi component sulfatic systems can only be really understood after comprehending the basic binary sub-systems. This work includes the experimental studies of the three sub-systems Na2SO4 - CaSO4, K2SO4 - CaSO4, and Na2SO4 - K2SO4 since there are variant and even contradictory results and interpretations in the literature (e.g. [1-11]). Differential Thermal Analysis (DTA) with simultaneous Thermo Gravimetry (TG) as well as X-ray Diffraction (XRD) measurements were done both to achieve the transition temperatures and the phase compositions in the sulfatic systems.

[1] J. H. Gladstone, Quart. Journ. of the Chem. Soc., 6 (1854) 106 [2] M. Le Chatelier, Bull. soc. chim., 47 (1887) 300 [3] K. Kubierschky, Hist., (1902) 404-413 [4] J. H. van’t Hoff and H. Barschall, Sitzungsber. K. Preuss. Akad. Wiss., 18 (1903) 359-371. [5] E. Jänecke, Z. Phys. Chem. Stoechiom. Verwandschaftsl., 64 [3] (1908) 343-356. [6] R. Nacken, Zentralbl. Mineral., Geol. Palaeontol., (1910) 262-271 [7] H. Müller, Neues Jahrb. Mineral., Geol. Palaeontol., Beilageband 30, (1910) 1-54. [8] W. Grahmann, Zeitschrift für Anorganische Chemie, 81 (1913) 257-314. [9] W. Eysel, American Mineralogist, 58 [7-8] (1973) 736 [10] J. M. Sangster and A. D. Pelton in “Critical Coupled Evaluation of Phase Diagrams and Thermodynamic Properties of Binary and Ternary Alkali Salt Systems”, Special Report to the Phase Equilibria Program, Part B: Evaluations for 54 common-ion binary systems involving (Li, Na, K) and (F, Cl, OH, NO3, CO3, SO4), American Ceramic Society; Westerville, Ohio; (1987) pp. 4-231. [11] N. Mofaddel, R. Bouaziz and M. Mayer, Thermochimica Acta, 185 [1] (1991) 141-153

188


[P66]Thermochemical Study of Rare Earth-Cadmium Systems: the System Gd-Cd

Herbert Ipser1, Rajesh Ganesan2

1University of Vienna 2Indira Gandhi Centre for Atomic Research

The pyrometallurgical process is one of the promising methods for reprocessing of spent nuclear fuel. In this process liquid Cd is used as cathode in the electrorefining step. The solubility and chemical activity of actinides and rare earth fission products in Cd are important parameters in the process. When the solute concentrations exceed their solubility limits in liquid Cd, intermetallic compounds between solutes and Cd are formed. An understanding of the chemical activity of Cd in such intermetallic compounds would help in optimizing the process parameters. Thus the thermochemical study of fission products-Cd systems assumes importance. In the present work, a detailed study of the thermochemical behavior of Gd-Cd alloys was carried out by an isopiestic vapor pressure method. The Gd samples were equilibrated in the temperature range 730-1122 K, at various known cadmium vapor pressures, viz., 3 to 133 mbar. Data points were obtained between approximately 0 and 85 at.% Cd. The obtained equilibrium phases were characterized and their cadmium activity was determined as a function of temperature and composition. From the temperature dependence of the activities, the thermochemical behavior of Gd-Cd alloys was derived. The derived data could be used as an input in the optimization of the Gd-Cd phase diagram by a CALPHAD approach.

Key words: Gd-Cd, Thermodynamic Properties; Vapor Pressure Measurements; Reprocessing of Nuclear Fuels.

189


[P67]Experimental investigation on the ternary compound and γ-Ni solvus

in the Ni-rich corner of the Nb-Ni-Ti system

Hongxiao Li, Y.P. Ren, N.N. Zhao, M. Jiang, G.W. Qin, S.M. Hao

Key Laboratory for Anisotropy and Texture of Materials, Ministry of Education, Northeastern University, Shenyang 110819, China

The equilibrium phase structures and compositions in the Ni-rich corner of the Nb-Ni-Ti system have been researched through the equilibrated alloy method by using scanning electron microscopy assisted with energy dispersive spectroscopy of X-ray, electron probe microanalysis, X-ray diffraction and transmission electron microscopy. It has been shown that one ternary compound with the composition about 10Nb-80Ni-10Ti (atomic fraction, %) exists in the Nb-Ni-Ti system, which could be in equilibrium with the Ni-based solid solution. The ternary compound could also be in three-phase equilibrium with γ-Ni+Ni3Nb at 1000 °C. It has the hexagonal structure with the structure parameters a=0.512nm and c=0.836nm. The solubility of Nb in the Ni-based solid solution increases for the third addition of Ti. The maximum solubility of Nb in γ-Ni is about 11.7at.%, and the total solubility of Ti and Nb in γ-Ni is about 14.2at.% at 1000 °C.

Acknowledgement: The financial support from the National Natural Science Foundation of China (Grant No. 50971037) is greatly acknowledged.

Key words: phase equilibrium; Nb-Ni-Ti; ternary intermetallic compound.

190


[P68]Design of new lead-free solders on the example of Sn-Zn-In

Janusz Pstrus, Tomasz Gancarz, Przemyslaw Fima

Institute of Metallurgy and Materials Science PAS, Krakow, Poland

Toxic properties of lead are the reasons for worldwide legislation, for example the RoHS EU directive, prohibiting the use of cadmium and lead in consumer products. Efforts were undertaken on finding replacements to conventional tin-lead solder, that would have similar properties. Literature data [1-3] point to eutectic Sn-Zn, as one of the most promising systems for soldering application. Unfortunately it is characterized by relatively poor wettability [4,5] and thus the addition of indium was proposed [6]. Thermodynamic analysis [7] and our own data show that the addition of In to Sn-Zn eutectic should not exceed 4 wt.%. DSC measurements were performed on the alloy containing 4 wt.% of indium. Wetting test procedure was developed based on initial measurements made on copper with traditional SnPb solder at 250 degrees with the use of rosin. Currently, wetting measurements Sn-Zn eutectic-based alloys Sn-Zn with additions of 0.5, 1, 1.5 and 4 wt.% of In are continued, with the use of industrial flux in nitrogen atmosphere. In order to progress with designing process, it is necessary to collect the results of dilatometric tests, electrical resistance, mechanical strength and structural studies.

Acknowledgement: This work is financed under the project “POIG.01.01.02-00-015/09-00 - ZAMAT - Advanced materials and technologies of their production - a task 4.3”, in the years 2010 - 2013.

Key words: Sn-Zn-In alloy; DSC; lead-free solder; wetting; solderability.

[1] Ganesan S., Pecht M., Lead-free Electronics, Wiley-Interscience (2006). [2] Glazer J., Int. Mater. Rev. 40 (1995) 65. [3] Abtew M., Selvaduray G., Mat. Sci. Eng. R. 27 (2000) 95. [4] Vianco P., Rejent R., J. Electron. Mat. 28 (1999) 1127. [5] Chen Z. et al. J. Electron. Mater. 35 (2006) 1734. [6] McCormack M. et al. Appl. Phys. Lett. 63 (1993) 15. [7] Vaynman S., Fine M.E., Scripta Mater. 41 (1999) 1269.

191


[P69]Solidus and liquidus measurements in the U-Zr binary system

K.C. Hari Kumar1, S. Balakrishnan2, K. Anathasivan2, S. Anthonysamy2, V. Ganesan2, P.R. Vasudeva Rao2

1Indian Institute of Technology Madras, Chennai, India 600 036 2Indira Gandhi Centre For Atomic Research, Kalpakkam, Chennai, India 603 102

Experimental data on the phase transitions in U-Zr system are useful in establishing the isothermal sections of the ternary U-Pu-Zr. The latter is relevant to metallic fast reactor fuels. Measurements on the solidus and liquidus in the U-Zr system are rather very limited [1-4]. Summers-Smith [1] had reported the solidus of U-Zr alloys (10, 30, 50 at.% Zr) by metallographic examination while the liquidus (above 40 at.% Zr) was measured by optical pyrometry. These values were later adopted by Masalski [5]. Leibowitz et al. [4] reported the solidus and liquidus temperatures for an alloy with a composition of 19.3 at% zirconium. Kanno et al. [6] arrived at the solidus and liquidus temperatures from their (measured) values on the activity of uranium in U-Zr alloys and Ogawa [7] calculated the same using the data reported in ref [5]. Maeda et al. [2] had measured the liquidus (24.4 and 39.3 at.% Zr) by Knudsen effusion mass spectrometry which is in commensurate with Summers-Smith [1]. Recently Kurata [8] optimized this phase diagram based on the data available in the literature. The solidus and liquidus was not measured over the entire range of composition by any of these authors and hence, the investigation of the same was undertaken by using the spot technique. For measuring the temperatures of phase transitions involving liquids in radioactive alloys beyond 1273 K, an experimental system based on Spot technique devised by Ackermann and Raugh [9] was set up in a glove box. This technique has been widely used to study the high temperature phase transitions that involve liquid in actinide bearing systems [9,10]. The accuracy in the temperatures of transitions was determined by measuring the melting points of pure Au, Cu, Ni, Pt and Zr. These melting points could be determined within ± 5 K.

Key words: Spot technique, solidus, liquidus, uranium, zirconium, temperature calibration, U-Zr.

[1] D. Summers-Smith, J. Inst. Met., 83 (1954-1955) 277. [2] A. Maeda et al., J. Alloys Comp. 179 (1992) L21-L24. [3] R.I. Sheldon et al., Bull. Alloy Phase Diagrams 10 (1989) 15-171. [4] L. Leibowitz et al., J. Nucl. Mater. 167 (1989) 76-81. [5] T.B. Massalski, Acta Met. 6 (1958) 243. [6] M. Kanno, M. Yamawaki, T. Koyama and N. Morioka, J. Nucl. Mater., 154 (1988) 154. [7] T. Ogawa and T. Iwai, J. Less_Comm. Met., 170 (1991) 101. [8] M. Kurata, IOP Conf. Series: Materials Science and Engineering 9 (2010) 012022. [9] R. J. Ackermann, E. G. Raugh, High Temp. Sci. 21 (1972) 161. [10] K. Ananthasivan, S. Anthonysamy, C. Sudha and A.L.E. Terrance, J. Nucl. Mater. 300 (2002) 217-229.

192


[P70]Experimental Determination and Thermodynamic Analysis of Phase Equilibria

in the Ni-W and Ni-Al-W systems

Kazuya Shinagawa, Toshihiro Omori, Katsunari Oikawa, Ikuo Ohnuma, Kiyohito Ishida, Ryosuke Kainuma


Ni-base superalloys strengthened by coherent precipitates of γ’ Ni3Al (L12) phase in γ (A1) matrix have been widely used as high temperature materials. Tungsten (W) is one of the essential alloying elements for improving high-temperature properties, and its effect on the phase equilibria and the mechanical properties has been reported by some researchers. However, even for the fundamental systems, such as the Ni-W binary and the Ni-Al-W ternary systems, phase diagrams have not been established in detail yet. Moreover, it was found that discrepancies between experimental results and calculation, especially in the Ni-Al-W system, were caused by inaccuracies in the respective sub-systems. In this study, eutectic, liquidus and solidus temperatures and phase equilibria among solid phases in the Ni-W binary system were determined experimentally. Isothermal section diagrams at temperatures between 900 and 1300 °C in the Ni-Al-W ternary system were also established. In the Ni-W system, the Ni4W phase is obtained by alloying method and the temperatures of the peritectoid reactions, (Ni) + NiW => Ni4W and (Ni) + (W) => NiW are confirmed to be 1031 °C and 1056 °C, respectively, by DSC measurement. It is interesting to note that partition behavior of W between γ and γ’ phases drastically changes with increasing W content and that the γ’ phase region extends to low Al content in the Ni-Al-W system. Thermodynamic evaluation of the Ni-Al-W system was carried out taking into account obtained experimental results. Calculated phase diagrams are in good agreement with experimental data.

Key words: γ’ Ni3Al (L12) phase, Ni-W binary system, Ni-Al-W ternary system, CALPHAD method.

193


[P71]Experimental determination of isothermal sections of Mo-Ni-Re

system at 1200°C and at 1600°C

Khurram Yaqoob, Jean-Marc Joubert

Chimie Métallurgique des Terres Rares, Institut de Chimie et des Matériaux Paris-Est, 2-8 rue Henri Dunant 94320 Thiais, France

Mo-Ni-Re system is of great interest in relation to the development of some nickel based superalloys. However if concentration of Mo and Re is too large, Frank-Kasper phases may form during exposure to high temperature [1-3]. These phases have adverse affect on the mechanical properties of the material. Therefore in order to avoid precipitation of these brittle intermetallic phases, it is important to determine the presence and homogeneity domains of different phases which may appear in the Mo-Ni-Re system. Comparison of the previous attempts [1-3] made for the experimental determination of Mo-Ni-Re phase diagrams revealed the presence of contradictory results. Therefore in order to develop a better understanding, a complete redetermination of Mo-Ni-Re system was carried out. Samples of different compositions were prepared, annealed, and investigated by means of metallography, X-ray diffraction and electron probe microanalysis. The isothermal section determined at 1200°C showed a large extension of binary σ (Mo-Re) and δ (Mo-Ni) phases into the ternary region and presence of a ternary phase was also observed. However, no ternary phase was observed in the isothermal section determined at 1600°C. For the ternary σ phase, a complete structural characterisation including the determination of ternary site occupancies was carried out for different ternary compositions. They will be compared to the calculated site occupancies [4] obtained by ab-initio calculations.

Key words: Mo-Ni-Re ternary system, isothermal section, phase diagram, Rietveld refinement, σ phase, ab-initio calculations.

[1] A. A. Kodentsov, S. F. Dunaev, E. M. Slyusarenko, E. M. Sokolovskaya and A. N. Priimak, Vestn. Mosk. Univ., Ser. 2., Khim., 28 (2) (1987) 153-158. [2] E. M. Slyusarenko, A. V. Peristyi, E. Y. Kerimov, M. V. Sofin and D. Y. Skorbov, J. Alloys Compd., 264 (1998) 180-189. [3] Y. Feng, R. Wang, K. Yu and D. Wen, Rare Met., 27 (1) (2008) 83-88. [4] J.-C. Crivello and J.-M. Joubert, to be published.

194


[P72]Microstructural aspects and computational thermodynamics of secondary

phase precipitation in Fe-Si 3%wt. steel

Leandro Nakamura Alves Vieira1, Marco Antonio da Cunha1, Fabricio Luiz de Alcantara1, Ronaldo Antônio Neves Marques Barbosa2

1Aperam 2Universidade Federal de Minas Gerais

The magnetic properties of electrical steels are affected by precipitation of secondary phases. The precipitates can work as a key controlled requirement as part of the manufacturing process or as an unwanted harmful residual in the final product. In this work, nitrides and sulfides precipitates in high permeability grain oriented electrical steels (HGO) were studied after soaking at different temperatures for long annealing time. The samples were encapsulated in a vacuum sealed quartz tube in order to avoid changes in the chemical composition during high temperature annealing and then the samples were analyzed by transmission electron microscopy (TEM), scanning electron microscopy (SEM), inductively coupled plasma mass spectrometry (ICP-MS) and also Optical Microscopy (OM). The Thermo-Calc software with a TCFE6 database was applied to access the multi-component phase equilibrium, and phase transformation for the system. The ICP-MS results showed close agreement with Thermo-Calc simulations for manganese sulfide precipitate, however aluminum nitride showed a different solubilization temperature. TEM results showed a cupper sulfide phase, and Thermo-Calc simulation considered cupper in solid solution in ferrite and austenite mainly.

Key words: electrical steel, grain oriented, sulfide, nitride.

195


[P73]Thermodynamic analysis of the Al-Cu-Er ternary system

Ligang Zhang1, Patrick J. Masset1, Libin Liu2

1Freiberg University of Mining and Technology, Centre for Innovation Competence Virtuhcon, Fuchsmühlen-weg 9, D-09596 Freiberg, Germany

2School of Material Science and Engineering, Central South University, Changsha, Hunan, 410083, P. R. China

For ternary and multicomponent phase diagrams, the experimental data is often scarce and sometimes contradictory. It is obviously an extremely time- and cost-consuming process to establish such phase diagrams solely by experimental work over wide ranges of compositions and temperatures. The CALPHAD method has proved to be a powerful tool to reduce the experimental effort by selecting small number of key experiments that are decisive for the thermodynamic description of the multicomponent system. In this work, experimental work has been done and combined with the CALPHAD method to generate a consistent thermodynamic description of the Al-Cu-Er ternary system, especially for Al-rich alloys. The viability of a procedure for the selection of multicomponent key samples is demonstrated for this multicomponent system. Dedicated thermal analysis with DSC on sealed samples was performed and the microstructure of solidified alloys was analyzed using SEM/EDX. The phase formation in ternary alloys is analyzed using the tool of thermodynamic equilibrium and Scheil calculations for the solidification paths and compared with present experimental data. The significant ternary solid solubilities of intermetallic phases are quantitatively introduced in the ternary Al-Cu-Er system phase diagram and validated by experimental data. And the experimental data of energy transformation (thermo effect) during the phase transformation are also simulated by our thermodynamic calculations.

Key words: Thermo analysis, Al-Cu-Er; Phase diagram, CALPHAD.

[1] L.G. Zhang, L.B. Liu, G.X. Huang, H.Y. Qi, B.R. Jia and Z.P. Jin “Thermodynamic assessment of the Al-Cu-Er ternary system”, CALPHAD, 32(2008) 527-534. [2] Ligang Zhang, Patrick J. Masset, Fuyong Cao, Fangui Meng, Libin Liu, and Zhanpeng Jin, “Phase relationships in the Al-rich region of the Al-Cu-Er system”, Journal of Alloys and Compounds, (509) 2010, p 3822-3831.

196


[P74]Physicochemical and thermodynamic properties of the GeSe2 -А2В6

(А2 = Hg; Cd; В6 = S, Te) systems

Mirsalim M. Asadov

Institute of Chemical Problems, National Academy of Sciences of Azerbaijan

With the purpose of definition of important parameters of intermediate phases and limited solid solutions of the threefold mutual Cd(Hg), Ge // S(Se),Te systems we investigated physicochemical and thermodynamic properties of the pseudo-binary GeSe2-CdTe, GeSe2-HgTe, GeSe2-HgS, GeSe2-CdS systems. The phase diagrams of GeSe2-А2В6 (А2 = Hg; Cd; В6 = S, Te) systems were plotted by the methods of differential thermal and X-ray diffraction analyses, by the measurement of electromotive force, microhardness and density. It is established, that phase equilibriums in the pseudo-binary GeSe2 - CdTe, GeSe2 - HgTe, GeSe2 - HgS, GeSe2 - CdS systems are characterized by formation of the limited solid solutions on basis of basic components and fourfold intermediate phases such as А2GeSe2Те2 and A4GeS4Se2: Cd2GeSe2Те2 (hexagonal system; a = 5.69; c = 11.32 Å), Cd4GeS4Se2, Hg2GeSe2Те2 (tetragonal system; а = 7.50; c = 36.48 Å), Hg2GeS2Sе2 (hexagonal system; а = 7.20; c = 36.64 Å), Hg4GeS4Se2 (monoclinic system; а = 12.38; b = 7.14; c = 12.40 Å). New dependences of the important physicochemical properties of solid solutions on basis of the GeSe2 crosscuts of GeSe2-А2В6 (А2 = Hg; Cd; В6 = S, Te) on composition are obtained. Thermodynamic characteristics of Cd2GeSe2Те2 and Hg2GeSe2Те2 phases were determined.

Key words: Mutual Cd(Hg),Ge // S(Se),Te systems, physicochemical and thermodynamic properties.

197


[P75]New intermetallic compounds in the Mg-Ni-Y system

Mohammad Mezbahul-Islam, Mamoun Medraj

Concordia University

Although the Mg-Ni-Y system is considered to be one of the promising candidates for Ni-metal hydride batteries and an important metallic glass system, it has not been investigated experimentally for the whole composition range. In this work, this system has been investigated experimentally at 400°C and new findings have been incorporated in a self-consistent database using the CALPHAD approach. Diffusion couples and key alloys have been used to investigate this system. Phase relations and solubility limits have been determined for the ternary phases using EPMA and XRD techniques. Six new ternary compounds, Ä1 to Ä6, have been found in this system where Ä6 has been found to have wide solubility range. The crystal structures of these compounds are being investigated in this work. The binary compounds Ni3Y and NiY are found to have similar solid solubility limits in the ternary system of approximately 2-3 at.% where Mg substitutes Y atoms. Whereas, the MgNi2 compound forms ternary solubility where Y substitutes Ni atoms with maximum solubility of approximately 4 at.%. The isothermal section of the Mg-Ni-Y phase diagram at 400°C has been constructed using the current experimental results and compared with the literature. The constituent binary systems have been modelled using the modified quasichemical model for the liquid phase. The ternary compounds have been included in the modelling and a self-consistent thermodynamic database has been constructed for this system. The ternary intermetallic compounds with homogenity range have been modelled using the sublattice model.

Key words: Phase diagram, Diffusion couple, Thermodynamic modeling, Modified quasichemical model.

198


[P76]Study of Phase Transformations and Phase Equilibria in the Ni-Sn-Zn System

Pavel Broz1, Georgui Vassilev,2 Vanya Gandova,2 Jří Bursík

1 Masaryk University, Faculty of Science, Department of Chemistry 2 University of Plovdiv, Faculty of Chemistry,

3 Institute of Physics of Materials, Academy of Sciences of the Czech Republic

Electronic, automotive, aerospace and other industries cannot be realized without solder materials. In the last decade a big effort has been made for replacements of lead containing solders which pose a serious threat from their toxicity point of view. One of the potential lead-free replacements are materials containing Ni, Sn and Zn. The knowledge on the phase transformations in the Ni-Sn-Zn system is, therefore, very useful. In the present work phase transformation and phase equilibria studies of the Ni-Sn-Zn system were performed by means of thermal analysis and analytical electron microscopy in the region of potential lead-free solder technology. The results together with previously published ones [1,2] will be used for a future CALPHAD phase equilibria type modeling based on a thermodynamic prediction of phase equilibria for binary subsystems [3-5] which is only available at the moment.

This work has been supported by the Ministry of Education of the Czech Republic under the project OC09010 (COST MP0602), MSM0021622410 and the University of Plovdiv (NPD) project RS09-HF-023.

Keywords: lead-free solders, CALPHAD, thermal analysis, phase analysis.

[1] J. Chang, S-K. Seo, H. M. Lee, J. Electron. Mater., 39 (2010)2643. [2] V. Gandova et al., Phase equilibria in the system Sn-Zn-Ni, Intern. J. Mater. Res. - in print [3] I. Ansara, A.T. Dinsdale, M.H. Rand, eds.,Thermochemical database for light metal alloys, vol. 2., COST 507, Luxembourg;1998. [4] J. Miettinen, CALPHAD, 27 (2003) 263. [5] H.S. Liu, J. Wang, Z.P. Jin, CALPHAD, 28 (2004)363.

199


[P77]Thermodynamic and thermophysical properties of Sn-Zn-In alloys

Przemyslaw Fima, Janusz Pstrus, Tomasz Gancarz


Worldwide studies on Pb-free replacement for traditional solders lead to two groups of alloys that can be used commercially. One of them is SAC alloys, whereas the other are alloys based on Sn-Zn eutectic. The great advantage of Sn-Zn eutectic alloy is that its melting temperature (471 K) is close to the melting temperature of Sn-Pb eutectic solder (456 K). The aim of this work is to study the effect of indium on thermodynamic and thermophysical properties of three Sn-Zn-In alloys of varying In content. Phase transitions and melting temperature were studied by means of the DSC technique. It was found that the addition of indium lowers melting temperature. The electric resistivity was studied by four points technique at 298 K. It was found that electric resistivity of Sn-Zn-In alloys is lower compared to Sn-Zn eutectic alloy. The electric resistivity studies over 298 to 423 K temperature range as well as thermal expansion studies by dilatometric technique over 223 to 423 K are planned. Acknowledgement.

This work is financed under the project “POIG.01.01.02-00-015/09-00 - ZAMAT - Advanced materials and technologies of their production - a task 4.3”, in the years 2010 - 2013.

Key words: Sn-Zn-In alloy; DSC; electric resistivity; thermal expansion.

200


[P78]Heat capacity at low temperatures and molar entropy of

stoichiometric Al2MnO4

Rogério Navarro Correia de Siqueira1, Roberto Ribeiro de Avillez1, Angelo Márcio de Souza Gomes2, Eduardo Granado Monteiro da Silva3

1PUC-Rio 2UFRJ 3LNLS

The heat capacity at constant pressure of the Al2MnO4 spinel was obtained by relaxation calorimetry on the range between 2 and 300 K. The data indicate the occurrence of a reversible transition around 33 K. The integration of the heat capacity from 0 to 298.15K resulted in an entropy value equal to 116. 4 J/mol.K at 298.15 K (25°C). This value is significantly greater than previous published values that did not consider the entropy associated with the low temperature transition anomaly detected at very low temperatures. The molar entropy associated with the transition was estimated to be 8.1 ± 0.3 J/mol.K. To analyze possible effects due to the crystalline structure, x ray diffraction experiment was performed with synchrotron radiation over the same temperature range. The thermal dependence of the lattice parameter was computed and the reasons for the heat capacity anomaly are discussed.

Key words: relaxation calorimetry, heat capacity at constant pressure, Al2MnO4.

201


[P79]Experimental Investigation of Phase Equilibria at Low Temperatures

(< 600 °C) in the Fe-Ni Binary System.

S. Shimenouchi, I. Ohnuma, T. Omori, R. Kainuma and K. Ishida

Department of Materials Science, Tohoku University, Sendai, JAPAN

In the Fe-Ni system, interesting phase equilibria at low temperatures below 600 °C have been proposed by experimental studies and predicted by thermodynamic calculations. For instance, the existence of the Nishizawa horn along the Curie temperature of the fcc (Fe, Ni) solution phase and that of the ordered FeNi (L10) phase were suggested by experimental investigation on meteorites [1] and predicted by the CALPHAD [2] and ab-initio [3] calculations. Furthermore, it was reported that the solubility of Ni in the α-Fe shows “retrograde solubility”, i.e., the Ni solubility increases with decreasing temperature below A3 point of pure Fe and starts decreasing again below 500 °C until the invariant reaction, γ-(Fe, Ni) => α-Fe + γ’-Ni3Fe (L12). The solubility of Ni in the α-Fe at low temperatures below 500 °C was determined by Goldstein et al. [4], Romig et al. [5] and Zhang et al. [6], in which small particles of γ-(Fe, Ni) precipitated in α’-Fe martensite matrix were examined by XRD, EPMA, TEM, etc. However, it seems that extra energies due to the martensite structure might cause the deviation of the solubility limit from the true equilibrium composition, especially at low temperatures. In this study, extremely deformed powders of the Fe-Ni alloys were equilibrated at low temperatures below 600 °C and phase equilibria were determined by a FE-EPMA (JEOL:JXA-8500F) with high special resolution (< 1 µm). Gas-atomized powders of Fe-Ni alloys were prepared and deformed extremely by converge milling method. Each powder sample was encapsulated in an evacuated quarts capsule and equilibrated at temperatures between 400 and 700 °C for various durations up to 3 months. After that, each powder sample was molded in a conductive resin, mechanically polished, and finished by a vibratory polisher with 0.1 µm diamond paste. Microstructure of cross section of the powder samples was examined and equilibrium compositions were determined by the FE-EPMA with low accelerating voltage of 6 kV. Dual-phase structures consisting of strain free particles of the α-Fe and γ-(Fe, Ni) phases, whose grain size reached up to 1 µm, were obtained after heat-treatment above at 400 °C for 3 months. Results of experiments suggest that the equilibrium compositions of the γ-(Fe, Ni) are in consistent with the previous data in literatures. However, it was confirmed that the Ni solubility in the α-Fe increases monotonically with decreasing temperature, which suggests that the “retrograde solubility” seems to be incorrect in the Fe-Ni system.

[1] C.-W. Yang, D.B. Williams, and J.I. Goldstein, J. Phase Equilibria, 17 (1996), 522. [2] I. Ohnuma, R. Kainuma and K. Ishida, CALPHAD and Alloy Thermodynamics, P.E.A. Turchi, A. Gonis and R.D. Shull Eds., TMS, (2002), 61. [3] T. Mohri, Y. Chen and Y. Jufuku, CALPHAD, 33 (2009), 244. [4] J.I. Goldstein and R.E. Ogilvie, Trans. Metall. Soc. AIME, 223 (1963), 2083. [5] A.D. Romig, Jr. and J.I. Goldstein, Metall. Trans. A, 11A (1980), 1151. [6] J. Zhang, D.B. Williams and J.I. Goldstein, Metall. Trans. A, 25A (1994), 1627.

202


[P80]Combinatorial technique for phase equilibria determination

of Pt-Fe-X (X=Al, In) sytems

Takashi Miyamoto, Ikuo Ohnuma, Kiyohito Ishida, Ryosuke Kainuma


In general, determinations of phase equilibria consume much time, manpower, money, etc. Therefore, it is important to pursue effective experimental methods to find out not only phase equilibria but also martensitic and magnetic transition boundaries in a simultaneous procedure. Combinatorial technique, which performs on diffusion triples (DT) to determine equilibrium compositions and the transition boundaries, has great potential to realize such as eco-experiments. In this study, applications of the combinatorial technique for phase equilibria determination in novel shape memory Pt-Fe-X (X=Al, In) alloys is introduced. A Pt/Fe diffusion couple (DC) prepared by clamping at 1000 °C was first diffusion treated at 1300 °C for 36 h. A cylindrical hole with a diameter of 1 mm was formed by drilling near the diffusion zone of the Pt/Fe DC, and some Al chips were inserted into the hole. DTs were finally obtained by diffusion-annealing at 1200 °C for 18h and at 1000 °C for 84 h in evacuated quartz tubes. The obtained DTs were chemically analyzed using an EPMA. According to experimental results on the Pt-Fe-Al system, the solubility of Pt for the β phase (B2) in the Fe-Al system reaches about 50 at.% at 1200 °C, which decreases rapidly with decreasing temperature down to 5 at.% at 1000 °C. On the other hand, in the Pt-Fe-In system, binary compounds, γ’-Pt3Fe (L12) and γ’-Pt3In (L12) make continuous solution, but no β phase (B2) was obtained. Furthermore, by microstructure examinations, martensite phases were identified in the β phase of the Pt-Fe-Al alloys and in the γ’ phase of the Pt-Fe-In alloys, and iso-Ms(= R.T.) concentration lines for the martensitic transitions were successfully determined.

Key words: combinatorial, Pt-based alloy, diffusion triple, martensite, phase equilibria.

203


[P81]Thermodynamic Modeling of the Cr-Si-B System and Experimental

Evaluation of Critical Points in the Cr-rich Region

Tales Ferreira Villela1,2, Vanessa Motta Chad1,3, Flávio Ferreira2, Gilberto Carvalho Coelho1,4, Carlos Angelo Nunes1, Nicolas David5, Jean-Marc Fiorani5, Michel Vilasi5

1Universidade de São Paulo (USP), Escola de Engenharia de Lorena (EEL), Pólo Urbo-Industrial Gleba AI-6, Caixa Postal 116, 12600-970, Lorena, São Paulo, Brazil

2Universidade Federal Fluminense (UFF), Escola de Engenharia Industrial Metalúrgica de Volta Redonda, Av. dos Trabalhadores 420, 27260-740, Volta Redonda, Rio de Janeiro, Brazil

3Universidade Federal de São Carlos (UFSCar), Departamento de Engenharia de Materiais (DEMa), Rod. Washington Luiz, km 235, 13.565-905, São Carlos, SP, Brazil

4Centro Universitário de Volta Redonda (UniFoa), Núcleo de Pesquisa, Campus Três Poços, Av. Paulo Erlei Alves Abrantes, 1325, Bairro Três Poços, 27240-560, Volta Redonda, Rio de Janeiro, Brazil

5Université Henri Poincaré Nancy 1, Institut Jean Lamour, Départment Chimie et Physique des Solides et des Surfaces, UMR7198 CNRS, Boulevard des Aiguillettes, BP 70239, 54506, Vandoeuvre-lès-Nancy, France

Materials with multiphase microstructures belonging to TM-Si-B systems (TM = transition metals) are good candidates for high-temperature structural applications. These alloys may be used both as substrate or coating materials. This work presents experimental results and thermodynamic modeling of the Cr-Si-B ternary system. Our own experimental data regarding the liquidus projection and the 1200°C isothermal section, both in the Cr-rich region, were used as the basis for the thermodynamic modeling. Binary and ternary samples were produced by arc-melting high-purity pieces of Cr, Si and B, followed by heat treatment at 1200°C for 200 hours. The samples were characterized by X-ray diffraction, scanning electron microscopy and electron microanalysis. The polymorphic transformation αCr5Si3-βCr5Si3, which according to Chang [1] occurs at 1505°C, has not been verified by differential thermal analysis experiments performed up to 1550°C. No thermodynamic modeling for this ternary system was found in the literature. The binary coefficients of Coughanowr, Ansara and Lukas [2] for the Cr-Si, Campbell and Kattner [3] for the Cr-B and Fries and Lukas [4] for the Si-B were used in the optimization of the ternary system. The model adopted for αCr5Si3 (T1) was the solution with three sublattices (Cr)4(Cr)1(Si,B)3 and for Cr5B3 (T2) was the solution with three sublattices (Cr)5(B,Si)2(B)1. The substitutional and interstitial models were used to describe the solubility of Si and B in the BCC structure, respectively, resulting in a solution with two sublattices (Cr,Si)1(B,Va)3. The experimental data are well reproduced by using the coefficients of the present optimization.

Keywords: Cr-Si-B System, Phase Diagram, Liquidus Projection, Isothermal Section, Thermodynamic Modeling.

[1] Y.A. Chang, Trans. Metall. Soc. AIME, 242 (1968) 1509-1515. [2] C.A. Coughnanowr, I. Ansara, H.L. Lukas, COST507 database for light metals alloys. [3] C.E. Campbell, U.R. Kattner, CALPHAD, 26(3) (2002) 477-490. [4] S.G. Fries, H.L. Lukas, COST507 database for light metals alloys.

204


[P82]Thermodynamic and physicochemical properties of Zn-Al-In alloys

Tomasz Gancarz, Przemyslaw Fima, Janusz Pstrus


Zn-Al-In solders containing 6 wt.% Al and 1-3 wt.% In are developed for ultra high temperature applications. The solder is designed to have a liquidus temperature between 650 and 660 K. The Al content improves electrical resistivity, but the In content is supposed to lower melting temperature and improve the spreadability. The aim of this work is to study the effect of indium on thermodynamic and physicochemical properties of three Zn-Al-In alloys of varying In content. Phase transitions and melting temperature were studied by means of the DSC technique. It was found that the addition of indium to Zn-Al eutectic alloy decreases their melting temperature. The electric resistivity was studied by four points technique at 298 K. It was found that electric resistivity of Zn-Al-In alloys is higher compared to Zn-Al eutectic alloy. The electric resistivity studies over 298 to 423 K temperature range as well as thermal expansion studies by dilatometric technique over 223 to 423 K are planned. Acknowledgement. This work in financed under the project “POIG.01.01.02-00-015/09-00 - ZAMAT - Advanced materials and technologies of their production - a task 4.3”, in the years 2010 - 2013.

Key words: Zn-Al-In alloy; DSC; electric resistivity; thermal expansion.

205


[P83]Experimental confirmation and thermodynamic analysis of existence of

fcc-type miscibility gap at high temperatures in some Cu-Ni base alloy systems

Y. Yu1, C.P. Wang1, X.J. Liu1, R. Kainuma2, K. Ishida2

1Xiamen University, China 2Tohoku University, Japan

Spinodal-hardening is one of the most important strengthening mechanisms in the Cu-Ni alloys, and is largely related to the face-centred cubic (fcc)-type miscibility gap (MG). The fcc-type MG in the Cu-Ni alloy system has been predicted to be at temperatures lower than 354.5 °C, suggesting to use spinodal-hardening in the Cu-Ni alloys is limited below 354.5 °C. Thus, to increase the existing temperatures of the fcc-type MG in the Cu-Ni base alloy systems by the addition of a third alloying element, is of both technical importance and academic interest. The present work systemically deals with the experimental confirmation of the fcc-type MG at high temperatures in the Cu-Ni-X (X=Mo, V, W, Nb, Ta) alloy systems by equilibrated alloy and diffusion couple methods, and thermodynamically analyzes the formation of the fcc-type MG at high temperatures in the Cu-Ni-X (X=Mo, V, W, Nb, Ta, Cr, Fe, Co) alloy systems by using the CALPHAD (CALculation of PHAse Diagrams) method. As an example, the calculated isothermal section of the Cu-Ni-V system at 1100 °C, is shown in Fig. 1(a), where a fcc-type MG (fcc1 + fcc2) exists in the Cu-Ni rich side. Typical fcc and (fcc1 + fcc2) microstructures were observed in the Cu47Ni47V6 (at.%) (Fig. 1(b)) and Cu46Ni46V8 (at.%) (Fig. 1(c)) alloys equilibrated at 1100 °C, respectively.

Key words: Fcc-type miscibility gap; Cu-Ni base alloys; Phase equilibria; Diffusion couple; CALPHAD.

206


[P84]Formation enthalpy of the BLi and B3Li intermetallic compounds by

solution calorimetric method

Dębski A., Gąsior W., Moser Z., Major Ł., Major R.

Institute of Metallurgy and Materials Science, Polish Academy of Sciences, 30-059 Kraków, 25 Reymonta Str., Poland

Solution calorimetric method was used for the determination of formation enthalpy of two intermetallic phases from the boron-lithium system. Preparation of the BLi and B3Li phases was conducted by direct reaction of boron and lithium at 773K. Next, the alloys obtained were short time annealed (about one hour) at 1073K followed by three days annealing at 873K. Samples of phases were analyzed by the X-ray diffraction and transmission electron microscopy. The results shown that the assumed phases were formed. Attempts of dissolution of the boron in Cu, Al and Se were undertaken however without success, because the long time was necessary for solution of boron in mentioned liquid solvents. The tests of solution of studied intermetallic phases in water were conducted and it was found that they fine dissolved in short time (about dozen minutes) and that the boron accumulated at the bottom of glass vessel. So, the water was chosen as the solvent for BLi and B3Li intermetallic phases. Calibration of the calorimeter was performed by dissolution of NaOH, LiOH, KMnO4 and ice in water and next the calorimeter was tested by measurement of the formation enthalpy of CaLi2 which was earlier measured by the dissolving it in Al and Sn bath (solvent). The results obtained were very similar for three different bathes so, the experiments with the solution of boron-lithium phases in water were undertaken. The heat effects of solution of Li, BLi and B3Li were measured and the formation enthalpy of the phases was calculated. The calorimetric studies of B-Li intermetallic phases have been carried out in the frame of research program Advanced Materials and their Production Technologies (ZAMAT) POIG.01.01.02-00-015/09-00.

207


[P85]Phase Relations in the Ca-Li System

Gasior W.*, W. Zakulshi, A. Debski

Institute of Metallurgy and Materials Science Polish Academy of Sciences

The Ca-Li alloys are a candidate for a safe and ecological hydrogen storage as an energy source for the application in the automobile industry. Additionally that system plays a very importante role in the aluminum and magnesium industries. The lack of thermodynamic data for the Ca-Li system both for the activities and for he heats of mixing in the liquid state was clearly emphasized in Bale, Pelton [1] assessment, as well as afther 20 years in the paper of Groebner, Schmid-Fetzer et al. [2] where the authors intended to model the thermodynamics and phase relations in he ternary Ca-Li-Mg system. The lack of the entire thermodynamic description of that system is not an effect of accidental negligence but is related to the extreme experimental difficulties, due to the high chemical reactivity of calcium and lithium with oxygen, hydrogen, nitrogen and the moisture.

Key words: thermodynamics, Ca-Li system, phase diagram calculation

[1] C.W. Bale, A.D. Pelton, Bull. Alloy Phase Diag., 8 (2) (1987) 125-127 [2] J.Groebner et al, Thermochim. Acta, 389 (2002) 85-94

208



First principle calculations

209


[P86]On the cluster expansion method

Cláudio Geraldo Schon1, Raymundo Arróyave2

1Escola Politécnica da Universidade de São Paulo, Brazil 2Texas A&M University

The Cluster Expansion Method (CEM), provides a simple and efficient way of predicting alloy phase diagrams using ab-initio calculations. It combines the calculation of a set of stoichiometric compound’s electronic structures at the ground state (T = 0K) using standard methods and a statistical mechanics formalism to extrapolate the thermodynamics of the system at finite temperatures. The method corresponds to a Fourier expansion in the configuration space, possessing thus important mathematical (topological and functional analytic) properties [1]. A key issue in the CEM is the choice of the truncation point, or the basis used, for the expansion (i.e. which compounds should be added). There are currently two approaches in use in the materials science community. One based on an algorithm developed by A. van de Walle and G. Ceder[2] requires introducing as many compounds as necessary for the self-consistent description of the energy of all possible configurations in the system (the so-called converged expansion). This approach requires introducing a large number of compounds (typically over 50) and the converged basis is system-dependent. The second approach is based on the choice of a small truncation point (a “basic cluster”) which is common to all systems of a given class (e.g. the irregular tetrahedron cluster in bcc lattices, see for example [3]). The first approach is mathematically sound, but requires the use of very specific computational tools. The second one is more flexible, but the expansion is not converged . There are evidences, however, suggesting that the main thermodynamic properties of a bcc system are already reproduced in the irregular tetrahedron approximation [4], hence the convergence of the expansion should only contribute with second or higher-order corrections over these results. We compare here ab-initio calculations for the bcc systems Co-Ga and Ni-Ga using both approaches, allowing the evaluation of their limitations

Key words: thermodynamic calculations, statistical mechanics, Ab-initio calculations, Phase diagrams.

[1] D. DeFontaine. Solid State Phys. 47 (1994) 33 - 176. [2] A. van de Walle, G. Ceder. J. Phase Eq. 23 (2002) 348 - 359. [3] N. Sodré et al. CALPHAD 33 (2009) 576 - 583. [4] - C. G. Schön, G. Inden. Acta Mater. 4

210


[P87]Ab initio study of thermodynamic, structural and electronic properties

of stable and metastable compounds in the Me-X systems (Me = Cu, Ni; X = In, Sn)

Críspulo E. Deluque Toro1, Susana Ramos de Debiaggi1, Gabriela F. Cabeza2, Armando Fernández Guillermet3

1Dpto. de Física. Facultad de Ingeniería. Universidad Nacional del Comahue. Neuquén. Argentina 2Dpto. de Física. Universidad Nacional del Sur. Bahía Blanca. Argentina

3Centro Atómico Bariloche e Instituto Balseiro. (8400) Bariloche. Argentina

The physico-chemical properties of Me-X (Me = Cu, Ni; X = In, Sn) based intermetallic phases (IPs) and related compounds have received considerable attention in connection with the search for new lead-free soldering materials. A particular motivation for the current research efforts is the lack of experimental information on the properties which are involved in the usual thermodynamic (CALPHAD-type) assessments, or in studies of the thermophysics of the various types of IPs. A possible way of facing these challenges would be to build a rather general database with consistent information on various kinds of physico-chemical properties. The purpose of the present contribution is to present a progress report on the development of a theoretical database of such characteristics using a density-functional-theory ab initio method implemented in the VASP code [1]. We present the calculated molar volume, bulk modulus and its pressure derivative, the energy of formation from the constituent elements and the electronic density of states of a variety of stable and metaestable Me-X IPs with Me=Cu,Ni and X=In,Sn. The results are compared with the available experimental data and previous ab initio results [2-5]. We also establish trends as a function of composition, which should be useful both in alloy design work and in the understanding of the phase-stability systematics.

Key words: Ab initio calculations; transition metals and alloys; Cu-In and Cu-Sn intermetallic phases; lead-free soldering alloys; Compound-Energy Model.

[1] G. Kresse, J. Furthmüller, Comput. Mater. Sci. 6 (1996) 15. [2] G. Ghosh, M. Asta, J. Mater. Res. 20 (2005) 3102. [3] G. Ghosh, Metallurgical and Materials Transactions 40A, (2009) 4. [4] S. Ramos de Debiaggi et al., J. Alloys Compd. (2011), in press. [5] S. Ramos de Debiaggi, G.F. Cabeza, A. Fernández Guillermet, submitted to Physica B.

211


[P88]Integrating finite temperature magnetism into ab initio free energy calculations

Fritz Kormann, Alexey Dick, Tilmann Hickel, Jörg Neugebauer

Max-Planck-Institut für Eisenforschung GmbH

The Gibbs free energy of a system is a fundamental quantity for predicting phase diagrams, finite temperature materials parameters, or kinetic barriers. An ab initio derivation of it makes a highly accurate evaluation of all excitation processes mandatory. One of the most challenging - but for many engineering materials crucial - contribution is coming from the magnetic degrees of freedom. We have developed an approach that eliminates shortcomings of conventional approaches and that is firmly based on an exact solution of an effective Heisenberg model employing the quantum Monte Carlo approach (QMC). We demonstrate the high accuracy achievable by the new approach by computing magnetizations, magnetic heat capacities and free energies for the magnetic pure elements Fe, Co, and Ni, and by extending it to magnetic compounds such as Cementite (Fe3C). Generally, an excellent agreement with experimental data is found.

Key words: First Principles, Ab initio, Magnetism, Gibbs Free Energy, Monte Carlo, VASP, Iron, Iron based alloys.

212


[P89]Ab initio Calculations on the Effect of Mn Substitution in Fe3AlC

Hanchul Kim, Ji-Young Noh

Sookmyoung Women’s University

The dispersion of k-carbide, (Fe,Mn)3AlC, within austenic matrix is expected to enhance the mechanical properties such as the ductility and the stability of alloys. The stoichiometric (Fe, Mn)3AlC has perovsktie-type structure (E21) in which iron (or manganese) atoms are located at the face centers, aluminium atoms are at the corners of the cube, and the carbon atoms take the body-center site of the cube. In this work, we have performed the density functional theory calculations using the projector augmented wave (PAW) potentials and the Perdew-Burke-Ernzerhof generalized gradient approximation (GGA) for the exchange-correlation functional. We calculated structural, magnetic, elastic, energetic, and electronic properties for both crystalline and supercell structures and investigated the changes in physical properties of κ-carbide accompanied by the varying contents of Mn. The crystalline Fe2MnAlC containing around 30% of Mn has the largest formation energy indicating that it is energetically most favorable. To understand the initial Mn alloying process, we substituted one Mn atom for one Fe atom in the 2x2x2 and the 2x2x4 supercell of Fe3AlC. We will present the Mn substitution induced changes in physical properties by analyzing the electronic structures. This work has been supported partly by the POSCO, Inc. and partly by the Strategic Supercomputing Support Program form Korea Institute of Science and Technology Information (No. KSC-2008-S02-0010).

Key words: Kappa carbides, density functional theory, Mn substitution.

213


[P90]Hybridizing SAFT and cubic EOS: what can be achieved?

Ilya Polishuk

Department of Chemical Engineering & Biotechnology, Ariel University Center of Samaria, 40700, Ariel, Israel

This study deals with creating a concept of the hybrid model gathering the advantages of both cubic EOS and SAFT approaches. The proposed idea is revision of the Chapman’s et al. SAFT by addressing the problem of the numerical pitfalls and the issue of the space available for dispersive interactions with further attaching the SAFT part by the cubic EOS’s cohesive term. It is demonstrated that the resulting model on one hand preserves the characteristic for SAFT accuracy in estimating the liquid compressibility, and on the other one - the characteristic for cubic equations capability of simultaneous modeling of critical and sub-critical data. Moreover, on the basis of the comprehensive set of thermodynamic properties of 8 challenging for modeling compounds (including n-hexatriacontane, water and methanol) it has been demonstrated that the proposed EOS has an over-all superiority comparing even to one of the most successful versions of SAFT, namely the SAFT-VR-Mie. These results indicate that tracking the trends established by experimental data and using the century-long experience with developing semi-empirical engineering models might sometimes be preferred over the exclusive relying on advanced molecular theories.

Key words: Equation of state, statistical association fluid theory, high pressure, heat capacity, sound velocity.

214


[P91]Ab-initio calculation of the BCC Fe-M (M = Ti, V, Cr, Zr, Nb, Mo): new results

on a correlation between compound stability and magnetism

Cláudio Geraldo Schon1, Pablo Guillermo Gonzales-Ormeño2, Ney Sodré3, Helena Maria Petrilli3

1Escola Politécnica da Universidade de São Paulo, Brazil 2Universidad Nacional Tecnologica del Cono Sur de Lima, Perú,

3Instituto de Física da Universidade de São Paulo, Brazil

The metastable phase diagrams of the bcc-based ordering equilibria in the Fe-M (M = Ti, V, Cr, Zr, Nb, Mo) systems have been calculated by the cluster expansion method, through the combination of Full Potential - Linear Augmented Plane Wave (FP-LAPW) electronic structure calculations and Cluster Variation Method (CVM) thermodynamic calculations in the irregular tetrahedron approximation. In spite of being neighbors in the periodic table, these six alloying elements result in radically different phase diagram topologies when alloyed with iron. This result contrasts with usual regularities (e.g. the Hume-Rothery rules) typically observed in other intermetallic compounds. The results are discussed considering the Electron Density of States (DOS) functions of the B2-FeM and D03-Fe3M compounds in the six systems and correlating their Formation Energies and the stability against the disordering reactions (B2 → A2-Fe + A2-M and D03-Fe3M → A2-Fe + B2-FeM) with the total magnetic moment. A linear correlation between compound stability ant total magnetic moment such that the highest magnetic momenta lead to the lowest compound stabilities.

Key words: Full potential, linear agumented wave (FPLAPD); Cluster Variation Method; magnetic interactions; order-disorder transformations.

215


[P92]Ab-initio calculation of the metastable bcc Al-M

(M = Sc, Ti, V, Cr, Y, Zr, Nb, Mo) phase diagrams

Pablo Guillermo Gonzales-Ormeño1, Ney Sodré2, Helena Maria Petrilli2, Claudio Geraldo Schon3

1Universidad Nacional Tecnologica del Cono Sur de Lima, Perú 2Instituto de Física da Universidade de São Paulo, Brazil 3Escola Politécnica da Universidade de São Paulo, Brazil

Transition metal aluminides, in particular those based on stable ordered intermetallic phases of the Ni - Al, Ti - Al and Fe - Al systems, are currently considered as good candidates the development of technological materials for structural applications involving high temperatures in aggressive environments. Technological materials, however, rarely consist of simple binary or even ternary systems, on the contrary, most of them consists of multicomponent thermodynamic systems with a large number of components. The present work is part of a major effort to build a multicomponent thermodynamic database dedicated to the description of the bcc phase in transition metal aluminides using ab-initio data, combining Full Potential - Linear Augmented Plane Wave (FP-LAPW) electronic structure calculations and the Cluster Variation Method (CVM) in the irregular tetrahedron approximation. Additionally important informations are gained about the thermodynamics of the bcc phase in the high-aluminum limit, hence in the limit of Aluminum alloys, for which there is a natural lack of experimental informations.

Key words: Intermetallics; Aluminum alloys; Full Potential-Linear Augmented Plane Wave (FP-LAPW), Cluster Variation Method (CVM).

216


[P93]First principles calculations of the copper silicide precipitates

R. Taniguchi1, S. R. Nishitani1, Y. Ohno2, and I. Yonenaga2

1 Department of Informatics, Kwansei Gakuin University, Gakuen 2-1, Sanda, 669-1337, Japan 2 Institute for Materials Research, Tohoku University, Katahira 2-1-1, Aoba-ku, Sendai, 980-85777, Japan

Very recently, the authors have reported the experimental observation of the precipitates of Cu3Si in a heavily copper doped Si. In this research, the energetic assessment of this precipitation behavior has been investigated by the first principles calculations.

Figure 1 shows two atomistic structure models of Cu3Si based on the Zintl phases [1]; one is the

D03 type structure called ‘twisted’, and the other is arranged on the position of Si sites called ‘parallel’. The reported stable intermetallic structure of Cu7Si2 is also calculated. The energy calculations with the outer and inner relaxes of atomistic structures are

performed by the VASP(Vienna Ab-initio Simulation Package) code.

Figure 2 shows that two Cu3Si phases are both more stable than the segregation limit of pure Cu and Si. Although the experimentally observed precipitates

show the very close structure with the Cu3Si twisted model, the parallel Cu3Si is more stable than the

twisted one. The outer shape of the parallel model, however, is very irregular, and its c-axis is 41.2% larger than the a-axis. Both models of Cu3Si show no band gap, which indicates that the phases are

conductor.

The other phase of Cu7Si2 is also more stable than the segregation limit. The tie line between pure Cu and Cu7Si2 drawn by the dashed line indicates that the twisted model of Cu3Si is metastable to Cu + Cu7Si2, and the parallel model of Cu3Si is most stable. Because the twisted Cu3Si shows cubic shape and the good lattice coherency with Si, it would appear as the structure of the precipitates.

[1] N. E. Christensen, Phys. Rev. B, 32 No.1, (1985), pp.209-228.

217


[P94]First-principles Study on Si Clusters Supported on

Carbon Nanotubes (CNTs) and Graphene

Vadym Kulish1, Man-Fai Ng2, Zhong Chen1, Ping Wu2

1School of Materials Science and Engineering / Nanyang Technological University, Singapore 2Institute of High Performance Computing, Singapore

Recently silicon has attracted a great attention among the novel anode materials for Li-ion batteries, because it has the highest known theoretical capacity (4200 mAh/g in Li22Si5 phase) and it is the second most abundant material on the Earth. The practical application of Si anodes, however, is hindered by the enormous volume changes (>400%) occurring in Si during lithiation, which eventually lead to the cracking of the anode material and large capacity fade. An attractive strategy to overcome the volume expansion problem is to build Si-based nanocomposites or hybrid materials. In both approaches, the choice of the secondary material and the strategy for the materials design play an important role. In the present study, we use density functional theory (DFT) to study hybrid nanostructures, consisting of Si-clusters adsorbed on the carbon nanotubes (CNTs) and graphene. We study the effects of Si cluster size and orientation, as well as the effect of support on the properties of hybrid systems. We first examine the structural stability of Si/CNT and Si/graphene systems. Adsorbed clusters exhibit different energetically favourable structural configurations, while the most stable one is the cluster orientation with three Si atoms, adjacent to CNT/graphene. We further investigate the effect of Si-Si spacing on the stability of Si/CNT complex. From the analysis of electronic structures, it is found that adsorption of Si clusters does not change the electronic properties of the support. Moreover, the density of state (DOS) of Si/CNT system shows more states around the Fermi level than in the pristine CNT. This indicates that Si/CNT should have higher conductivity than its standalone parts (Si and CNT), which is beneficial for the Li-ion battery application.

Key words: Hybrid nanostructures, silicon clusters, Li-ion battery anode, DFT.

218


[P95]Predicting grain boundary structures and properties from ab initio molecular

dynamics and first-principles calculations

W.Y. Wang1, H.Z. Fang1, S.L. Shang1, Y. Wang1, Z.K. Liu1, Suveen Mathaudhu2

1Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA 16802, USA

2Materials Science Division, US Army Research Office Research Triangle Park, NC 27709, USA

A solid-liquid interface model is developed to predict grain boundary structures through ab initio molecular dynamic calculations. Using the coincidence site lattice model for Cu, the twinning [ ]( )3 011 111∑ and [ ]( )5 001 210∑ grain boundary structures are created and their related energies from our calculations match well with the previous reported results. Additionally, entropy, enthalpy and heat capacity of these grain boundaries are studied in terms of quasiharmonic approach with the vibrational contribution to Helmholtz free energy described by the Debye model. The newly developed approach is used to predict the grain boundary structures with arbitrary orientations.

219


[P96]First principles calculations of 18R Mg alloys

Yoshihiro Masaki1, M. Sugimoto1, Y. Yamamoto1, Y. Miyamoto1, S. R. Nishitani1

1 Department of Infomatics, Kwansei Gakuin University, Gakuen 2-1, Sanda, 669-1337, Japan

Long periodic stacking ordered (LPSO) Mg alloys show excellent mechanical properties, and the the mechanism of such a query microstructure formation is the one of the key issues of the newly developing light-weight Mg materials. The LPSO Mg alloys, its typical composition of Mg97Zn1Y2, show 18R structure with the long period stacking sequence of the mixture of hexagonal and cubic layers and added Zn and Y atoms are enriched in cubic layers. In this research, we have investigated the energetic assessment of these structures by the first principles calculations in order to reveal the mechanism of LPSO formation in Mg alloys. We have performed the atomistic model constructions using MedeA and the structure energy calculations using Vienna Ab Initio Simulation Package (VASP) code. The cut-off energy was 600 eV and the k-point meshes were determined from the shapes of models.

Fig. 1 shows the energies of the stacking sequence ratios between pure hexagonal(2H) to pure cubic

(3C) stacking sequences. The 18R structure locates on the line between 2H and 3C, and either do the

other structures, which indicates that the inter-layer interactions are short and good estimations of linear combination between hexagonal and cubic

stacking energies.

Fig. 2 shows the energy differences between cubic and hexagonal structures of the different sizes with

the Zn and Y additives. The energies are almost linearly dependent on the system size, which are expected from the linear dependency among 2H

and 3C. The exceptions are observed in 24 atoms models with Y and Y+Zn, which indicate that

these structures are relatively more stable than the simple averages. The other detailed discussions will be given on the poster. We will also report

the results of Monte Carlo simulation of atomistic level LPSO formations.

220


[P97]First principles calculations on vibration free energies of SiC polytypes

Yosuke Yamamoto1, S.R.Nishitani1, and T.Kaneko2

1 Department of Informatics, Kwansei Gakuin University, Gakuen 2-1, Sanda, 669-1337 Japan. 2 Department of Physics, Kwansei Gakuin University, Gakuen 2-1, Sanda, 669-1337 Japan.

SiC has been recently focused on the next generation materials for the power electronic devices due to its excellent physical and chemical properties. SiC shows many polytypes such as, 3C, 4H and 6H. The phase stabilities of these polytypes are still under discussions. The novel crystal growth method of SiC polytypes, so-called Metastable Solvent Epitaxy(MSE), has recently been developed by the authors, in which a similar mechanism to that of the high-pressure synthesis of diamond is used. The driving force of the epitaxial growth of stable 4H-SiC is the metastability of the polytype of SiC. The stability of the polytypes have been explored by the first principles calculations with the phonon free energy, but the difference is very small. In this research, the authors investigate the accuracy of the calculations. The VASP (Vienna Ab-initio Simulation Package) code has been used. After adjusting some parameters of the VASP code, the major controlling parameter on the total energy has been appeared to be the cut-off energy. Fig.1 shows the cut-off energy dependence of the total energy of 3C-SiC; the energies approach to a value of 1000eV or above of the cut-off energy. Fig.2 shows the temperature dependency of the phase stabilities of 3C-SiC measured from 4H-SiC. Two lines calculated by the cut-off energies of 600eV and 400eV are shown by the solid and dashed lines, respectively. The dashed line with the cut-off energy of 400eV shows that 4H-SiC is more stable than 3C-SiC on the entire temperature range. The solid line with the cut-off energy of 600eV shows

(i) 3C-SiC is stable at the lower temperatures,(ii) 4H-SiC is stable at the higher temperatures, and(iii) the transition temperature is located around at 1000K.These results are consistent with the experimental ones.

Fig. 1 Cut-off energy dependence of the total energy of 3C-SiC.

Fig. 2 Temperature dependency of the phase stabilities of 3C-SiC measured from 4H-SiC. The

solid and dashed lines were calculated with the cut-off energies of 600eV and 400eV, respectively.

221


[P98]Effects of sulfur and nitrogen impurities on the properties of the

solid oxide fuel cell anode materials

Oleksandr Malyi1, Zhong Chen1, Ping Wu2

1School of Materials Science and Engineering, Nanyang Technological University, Singapore, 2Institute of High Performance Computing, Singapore

Solid oxide fuel cells (SOFC) are one of the most promising energy conversion devices that produce electricity directly from oxidizing a fuel. However, its high cost is a significant limitation to its residential and commercial applications if pure hydrogen is used as the fuel. As a result, the search of cheaper SOFC materials and cheaper fuels becomes vital. In the past few years, various types of fuels have been considered as alternative fuels to hydrogen, and it has been shown that impurities (carbon, sulfur, nitrogen etc.), contained in them, may not only change SOFC performance significantly but also lead to the degradations of SOFC performance. Therefore for the development of new SOFC anode materials the studies of the effect of impurities on the SOFC materials are needed. Based on an ab initio density functional theory, we evaluate the effects of sulfur and nitrogen impurities on the properties of SOFC anode materials. It is observed that sulfur and nitrogen impurities have tendency to place at the zirconia surface that may have significant effect on the stability of metal/zirconia interfaces, and as a result, on the particle agglomeration rates. The study of the effect of sulfur impurity on the stability of metal/c-ZrO2 interfaces has proposed an explanation for the experimentally observed degradation of SOFC performance in case of using sulfur-containing fuels (at low concentration of sulfur impurity in a fuel gas) and Ni/YSZ anode materials. Finally, based on the first principle studies of the effects of sulfur and nitrogen impurities on mixed conductor properties we suggest criteria for the intelligent design of sulfur/nitrogen tolerant anode materials.

Key words: SOFC, anode, density functional theory.

222



Modeling and fundamental aspects

223


[P99]Critical evaluation of the sulfuric acid - water system in wide

concentration and temperature range

Hannu Sippola

Aalto University, School of Science and Technology, Department of Materials Science and Engineering

Recently, the modified Pitzer equation [1], i.e. NPL modification, first presented in CALPHAD 2008 conference at Saariselkä, Finland, was used to model concentrated sulphuric acid solutions up 15 mol/kg at temperature range 0-50 °C [2]. Following four Pitzer parameters were found essential in the modelling of the sulfuric acid–water system:

• Cφ between H+ and SO4- ions,

• β(0) and β(1) between H+ and HSO4- ions, and

• θ between SO4- and HSO4

- ions.The temperature dependency of all parameters was a + b/T. Two five parameter sets including these

parameters and enhanced by β(0) (H+ / SO4-) or Cφ (H+ / HSO4

-), were found to fit the experimental data equally well but the latter has better ability to extrapolate the stoichiometric osmotic coefficients up to 27 mol/kg solution at 25 °C. Furthermore, this set is also able to reproduce the stoihiometric osmotic coefficient data obtained by more complicated model of Clegg and Brimblecombe [3] up to 40 molal solutions at three temperatures 0, 25 and 50 °C with maximum deviations of 0.025, 0.012 and 0.021, respectively, which is excellent result considering that the maximum molalities used in parameter assessment were 15 mol/kg at 25 °C and 8 mol/kg at other temperatures. However, there was little difference in quality of the assessment between studied K2 equations. The importance of choosing the best K2 equation for sulfuric acid is a key factor for the further development of model for acidic systems where sulfate is involved. The scope of this study is to continue the critical evaluation of sulphuric acid -water system by extending the concentration and temperature range at least up to 20 mol/kg and 175 °C and critically evaluate the most suitable K2 equation to describe dissociation reaction of the bisulfate ion

HSO4- = SO4

2- + H+ K2 = a(SO42-) a(H+) / a(HSO4

-) (1)

Keywords: Sulfuric acid, Thermodynamic modelling, Modified Pitzer equation, Osmotic coefficient, Activity coefficient.

[1] Pihlasalo J, Davies H, Taskinen PA, Validation of a new Pitzer type model and database for aqueous solutions with Outotec HydroCopperTM process data. Saariselkä, Finland, 2008. [2] Sippola H. Thermodynamic Modelling of Sulphuric Acid Solutions. Bio- & Hydrometallurgy ‘10: Cape Town, South Africa, 2010. [3] Clegg SL, Brimblecombe P. Application of Multicomponent Thermodynamic Model to Activities and Thermal Properties of 0-40 mol kg-1 Aqueous Sulfuric Acid from <200 to 328 K. J Chem Eng Data 1995;40:43-64.

224


[P100]Predicting thermodynamic properties of ternary systems by means of

finding a function value inside a Gibbs triangle

Jolanta Romanowska

Rzeszów University Of Technology

This paper presents a new numerical approach to modeling of ternary systems on the basis of thermodynamic properties of binary systems included in the investigated ternary system. ternary interaction parameters in the Muggianu extension of the Redlich - Kister formalism are calculated numerically by use of the Excel program and Solver. Unless all binary parameters are known, the idea of calculating parameters can be regarded as solving an equation, where all boundary conditions (binary ij alloys) are known. This approach is contrary to fi nding a function value outside a certain area, if the function value inside this area is known. The approach proposed in this paper is as follow: if we know all boundary conditions, values on all legs of the Gibbs triangle and a function inside the triangle, we fi nd a function value inside the triangle. Results of calculations were compared with the literature data for Ag-Au-Bi, In-Sn-Zn and Cu-Fe-Sn systems.

Key words: Thermodynamics, predicting ternary properties.

[1] Y.-M. Muggianu, M. Gambino, J.-P. Bros, J. Cnim. Phys., 72 (1975) 83-88. [2] O. Redlich, T. Kister, Ind. Enging. Chem., 40 (1948), 345-348. [3] E. Zoro, C.Servant, B. Legendre, CALPHAD, 31 (2007) 89-94. [4] Y. Ciu, X.J. Liu, I. Ohunuma, H. Ohtani, K. Ish.

225



Nanomaterials

226


[P101]Calculation of Ag-Sn Phase Diagram Including the Size Effect

Adela Zemanova1, Jří Bursík1, Jiří Sopousek2, Jan Vřesťál2, Pavel Broz2

1Institute of Physics of Materials, Academy of Sciences of the Czech Republic, Zizkova 22, 616 62 Brno, Czech Republic,

2Masaryk University, Faculty of Science, Department of Chemistry, Kotlarska 2, 611 37 Brno, Czech Republic

CALPHAD approach is a very useful technique for calculation of phase diagrams of bulk materials based on thermodynamic database containing data such as chemical potentials of pure substances and excess Gibbs energy of mixtures as a function of composition, temperature and pressure. In order to extend the use of CALPHAD approach to small metallic particles on sub-micron and nano scale, due to the surface effect, the chemical potentials and the excess Gibbs energy should be expressed with an additional parameter: the particle size. In this study, the nanoalloy Ag-Sn binary phase diagram was calculated by using the CALPHAD method. Silver-tin alloy is one of the promising alternatives for Sn/Pb solders. The calculated nanoalloy phase diagram was verified using experimental data from the literature and also the data from own experimental work.

Acknowledgement: Financial support of the Czech Science Foundation (grant No. 106/09/0700) and of Ministry of Education, Youth and Sports of the Czech Republic (grants Nos. LD11024, 11046 and MSM0021622410) is gratefully acknowledged.

Key words: Nanoalloys, phase diagram, CALPHAD method.

227


[P102]Calculation of nanoalloys phase diagrams

Jan Vřesťál1, Jiří Pinkas1, Jiří Sopousek1, Pavel Broz1, Jří Bursík2

1Masaryk University, Fac.Sci., Dept.Chemistry, Kotlarska 2, 611 37 Brno, Czech Republic, 2Institute of Physics of Materials ASCR, Zizkova 22, 616 62 Brno, Czech Republic

Calphad-type calculation is most effective and useful tool for practical applications because thermodynamic data for various multi-component systems are available. First-principles approach is restricted to the several hundred atoms only and molecular dynamic simulations have a limitation when applied to multi-component systems. Calphad-type calculations make us possible to take surface energy of nanoparticles into account and to calculate phase stability in this situation. Procedure of including surface dependent parameters of pure components and of alloys into Calphad modeling was explained on the model system Ag-Au [1]. In the present contribution, the Cu-Ni and Ag-Cu systems were used as a systems with practical importance in electronic industry for calculation of phase diagram of nanoalloys - nanoparticles of different composition. Calculated nanoalloy phase diagram could be verified by calorimetric determination of temperatures of phase transformation of synthesized nanoalloys, characterized by electron microscopy.

Acknowledgement: Financial support of Ministry of Education, Youth and Sports of Czech Republic under grant Nos. 11046 and MSM0021622410 and Czech Science Foundation of grant No. 106/09/0700 are gratefully acknowledged.

Key words: nanoalloys, phase diagram, Cu-Ni system, Ag-Cu system.

[1] J. Park, J. Lee,: Calphad, 32 (2008) 135.

228


AAboufaris E., S. Mohammed ................................................ 154

Abreu, Hamilton Ferreira Gomes de .................................... 130

Abrikosov, Igor ...................................................................... 28

Ågren, John ............................................................................ 40

Ahmadi, M.R. ........................................................................ 49

Alcantara, Fabricio Luiz de .................................................. 194

Alling, Björn .......................................................................... 28

Almeida, Daniel S. de .......................................................... 174

Anathasivan, K. .................................................................... 191

Anthony, Edward J. ................................................................ 73

Anthonysamy, S. .................................................................. 191

Antoni-Zdziobek, Annie ...................................................... 183

Aranda, Lionel ......................................................... 55;128;185

Ardell, Alan J. ........................................................................ 96

Arróyave, Raymundo ........................................................... 209

Asadov, Mirsalim M. ........................................................... 196

Asano, T. .............................................................................. 179

Avillez, Roberto Ribeiro de ............................ 121;131;171;200

Azougen, Rachid .................................................................. 154

BBa, M.................................................................................... 128

Ba, Moussa ............................................................................. 55

Bacalhau, José Britti ............................................................ 125

Balakrishnan, S. ................................................................... 191

Bale, Christopher ................................................................... 99

Barbosa, Celso Antonio ....................................................... 125

Barbosa, Ronaldo Antônio Neves Marques ......................... 194

Baricco, M. ........................................................................... 144

Beilmann, M. ......................................................................... 69

Beneš, O. ........................................................................... 68;69

Berezutsky, V........................................................................ 157

Berthod, Patrice ................................................. 55;128;129;185

Biao Hu .................................................................................. 62

Bielefeldt, W. V. ................................................................... 134

Björkman, Bo ....................................................................... 145

Böttger, Bernd ........................................................................ 80

Bracarense, A.Q. .................................................................. 171

Bratberg, J. ........................................................................... 172

Brocchi, Eduardo de Albuquerque ....................................... 131

Broz, Pavel .................................................63;104;198;226;227

Bulanova, M.V. .................................................................... 158

Bursík, Jří ............................................................... 198;226;227

Burton, Benjamin ................................................................... 21

Byeong-Joo Lee ..................................................................... 33

CC.P. Wang ................................................................. 70;173;205

Cabeza, Gabriela F. ......................................................... 26;210

Campos, Marcos Flavio de .................................... 126;152;180

Capurro, Constantino ............................................................. 79

Castro, F. ................................................................................ 81

Castro, Jose Adilson de ........................................................ 180

Černý, Radovan ...................................................................... 42

Chad, Vanessa Motta ............................................................ 203

Chandra, D. ............................................................................ 42

Chandra, Dhanesh .................................................................. 27

Chang, Keke ......................................................................... 164

Changjun Wu ................................................................ 140;186

Changrong Li ....................................141;142;160;165;166;167

Chan-Hee Han ........................................................................ 33

Chao-Hao Hu ....................................................................... 162

Chartrand, Patrice ...................................................... 91;92;150

Chaumat, V. .......................................................................... 122

Chien, W-M ............................................................................ 42

Choi, Byung-Kwon ................................................................ 66

Choi, Hanshin ........................................................................ 60

Chonghe Li ............................................................................. 43

Chowdhary, S.G. .................................................................. 181

Christine, Gueneau ................................................................. 71

Chunju Niu ........................................................................... 142

Chunsheng Sha................................................................ 62;163

Cicutti, Carlos ........................................................................ 79

Coelho, Gilberto Carvalho ..................................... 174;184;203

Colinet, Catherine ............................................................. 22;35

Corso, A. Dal.......................................................................... 52

Corvalan, Carolina ............................................................... 177

Crivello, Jean-Claude ................................................... 36;37;42

Crozet, Coraline ................................................................... 183

Cuiping Guo ........................................74;141;142;165;166;167

Cuiyun He ......................................................................... 44;62

Cunha, Marco Antonio da ............................................. 170;194

Cuppari, Márcio Gustavo di Vernieri ................................... 151

Authors Index

229


DDan Cai .................................................................................. 97

Dandan Liu ............................................................................. 50

David, Nicolas ............................................................... 184;203

Debiaggi, Susana Ramos de ............................................ 26;210

Dębski, A.............................................................................. 206

Debski, A.............................................................................. 207

Decterov, Sergei A. ........................................................... 93;99

Desgranges, C. ....................................................................... 67

Dia, Ahmed ..................................................................... 55;128

Dick, Alexey ........................................................................ 211

Dinsdale, Alan ...................................................................... 104

Dongdong Zhao .............................................................. 62;161

Dongping Tao ....................................................................... 147

Dovbenko, O. ......................................................................... 44

Duchesne, Marc A. ................................................................. 73

Dumas, Jean-Christophe ................................................. 75;120

Dupin, Nathalie ...................................................................... 88

EEidenberger, E. ....................................................................... 47

Ekholm, Marcus ..................................................................... 28

Eleno, Luiz ........................................................................... 151

Emmerlich, Jens ..................................................................... 31

Ende, Marie-Aline Van .......................................................... 60

Engström, A. ........................................................................ 172

Essadiqi, Elhachmi ............................................................... 102

FFabrichnaya, Olga .................................................................. 57

Falahati, A. ............................................................................. 49

Farina, Alexandre Bellegard .................................. 125;126;152

Fartushna, Yu.V .................................................................... 158

Ferreira, Flávio ..................................................................... 203

Fima, Przemyslaw .................................................. 190;199;204

Fiorani, Jean Marc ........................................................ 184;203

Fitzner, Krzysztof ................................................................... 56

Flandorfer, Hans ................................................................... 137

Fries, Suzana G. .................................................... 37;52;58;106

GGan, S.X. .............................................................................. 173

Gancarz, Tomasz .................................................... 190;199;204

Gandhi, Ashutosh S. ............................................................. 119

Gandova, Vanya ................................................................... 198

Ganesan, Rajesh ................................................................... 188

Ganesan, V. .......................................................................... 191

Garzel, Grzegorz .................................................................. 105

Gąsior, W. ............................................................................. 206

Gasior, W. ............................................................................. 207

Gaune-Escard, Marcelle ....................................................... 175

Gheribi, Aimen ..................................................................... 150

Ghosh, Suddhasattwa ........................................................... 148

Gierlotka, Wojciech................................................................ 56

Glensk, Albert ........................................................................ 19

Gomes, Angelo Márcio de Souza ......................................... 200

Gómez-Acebo, T. ................................................................... 81

Gong, Weiping ..................................................................... 175

Gonzales-Ormeño, Pablo Guillermo ...................................... 20

Grabowski, Blazej .................................................................. 19

Groebner, Joachim ............................................................... 101

Grushko, B. .......................................................................... 143

Guendouzi, Mohamed El ..................................................... 154

Gueneau, Christine ................................................................. 88

Guillermet, Armando Fernández ..................................... 94;210

Guimarães, Nara M. ............................................................. 174

Guimarães, Rodrigo Freitas ................................................. 130

Gupta, M. ............................................................................... 42

HH.Z. Fang ............................................................................. 218

Haiyang Niu ........................................................................... 63

Haiying Qi ............................................................................ 146

Hallstedt, Bengt .................................................................... 107

Hamdouny, Ihssane .............................................................. 154

Hamini, Y. ............................................................................ 185

Hammerschmidt, T. ................................................................ 37

Hampl, Milan ....................................................................... 101

Hang Wang ............................................................................. 45

Hao Tu ........................................................................... 140;186

Hao, S.M. ...................................................................... 103;189

Haoping Peng ................................................................ 140;186

Héricher, L. .......................................................................... 185

Hestin, Ophélie ...................................................................... 55

Heyrman, Matthias ................................................................. 92

Hickel, Tilmann.......................................................... 19;52;211

Hindler, M. ........................................................................... 109

Hodaj, Fiquiri ....................................................................... 122

Hong Bo ............................................................................... 149

Honghui Xu ................................................................ 32;62;163

Hongxiao Li ......................................................................... 189

230


Hosseinifar, Mehdi ................................................................. 48

Huai-Ying Zhou ................................................................... 162

Huang, Guoxing ................................................................... 146

Hug, Gilles ............................................................................. 22

Hughes, Robin W. .................................................................. 73

Hultman, Lars ................................................................... 85;98

IIina, Vaajamo ....................................................................... 159

Ipser, Herbert ........................................................... 89;137;188

Iribarren, Manuel ................................................................. 177

Ishida, Kiyohito .....................................51;87;192;201;202;205

Ivanov, M. ............................................................................ 157

JJacobs, M. H. G. ..................................................................... 52

Jak, Eugene ....................................................................... 93;99

Jansson, Bo ....................................................................... 85;98

Jeff Chen ................................................................................ 93

Jelkina, Galina ...................................................................... 145

Jendrzejczyk-Handzlik, Dominika ......................................... 56

Je-Wook Jang ......................................................................... 33

Jianchuan Wang ..................................................................... 32

Jiang, M......................................................................... 103;189

Jianhua Wang ................................................................ 140;186

Jinming Liu .......................................................................... 167

Jo, Yun Hwan ......................................................................... 59

Joubert, Jean-Marc .............................................. 36;37;153;193

Jund, Philippe ......................................................................... 22

Jung, In-Ho ............................................................................ 60

Jung, Inyu ............................................................................... 59

Jung, Yang-Il .......................................................................... 66

KKai Li ................................................................................... 161

Kainuma, Ryosuke .....................................87;192;201;202;205

Kajihara, M. ......................................................................... 179

Kaneko, T ............................................................................. 220

Kang, Youn-Bae ................................................................... 150

Kapush, D. ........................................................................... 143

Kattner, U. R. ......................................................................... 52

Kattner, Ursula R. ................................................................ 106

Kaufman, Larry ...................................................................... 46

Kevorkov, Dmytro ............................................................... 150

Khan, Atta Ullah .................................................................... 63

Kim, Hanchul ....................................................................... 212

Kim, Hyun-Gil ....................................................................... 66

Kim, In Gee .......................................................................... 124

Kim, Taek-Soo ....................................................................... 60

Kjellqvist, L. ........................................................................ 172

Kobertz, D. .................................................................... 110;187

Konings, R. J. M. ................................................................... 68

Konings, R. ............................................................................ 69

Konings, R.J. .......................................................................... 71

Konrad, Joachim .................................................................... 82

Kormann, Fritz ..................................................................... 211

Korniyenko, K. ..................................................................... 143

Korzhavyi, Pavel .................................................................... 38

Kozeschnik, E. .................................................................. 47;49

Kozlov, Artem ...................................................................... 101

Kroupa, Ales .......................................................... 104;137;138

Kudin, V. .............................................................................. 157

Kudin, V.G. .......................................................................... 158

Kulish, Vadym ...................................................................... 217

Kumar, K.C. Hari ..................................... 119;148;178;181;191

Kyu-Seok Han ........................................................................ 33

LL.J. Zhang ............................................................................ 172

Lage, Meire Guimarães ........................................................ 127

Lamb1, J. ................................................................................ 42

Landa, Alexander I. ................................................................ 34

Landgraf, Fernando J G ....................................................... 180

Lang, P............................................................................... 47;49

Latroche, M. ........................................................................... 42

Lay, Sabine ........................................................................... 183

Lee, Hyuck Mo ...................................................................... 59

Lee, Jee Yong ....................................................................... 124

Lee, Sung Hoon ..................................................................... 30

Legut, Dominik .................................................................... 138

Leitner, H. .............................................................................. 47

Li Chen ................................................................................. 164

Li, HX .................................................................................. 103

Libin Liu ................................................................ 146;149;195

Ligang Zhang ........................................................... 72;149;195

Lijun Zhang ....................................................................... 50;97

Liling Jin .............................................................................. 150

Lima, Belmira Benedita de .................................................. 184

Lin, Shih-kang ...................................................................... 156

Lind, Hans .............................................................................. 28

Lindahl, Bonnie .................................................................... 139

Lins, Jefferson Fabricio Cardoso ......................................... 126

231


Lu, Dennis Y........................................................................... 73

Lü, Dongxian ....................................................................... 166

Lutsyk, V. ............................................................................. 133

MMacchi, Arturo ....................................................................... 73

Maehsima, Takashi ............................................................... 132

Magalhães, Humberto Luiz Gama de .................................. 123

Maheswari, N. ...................................................................... 181

Mailliart, O. .......................................................................... 122

Major, Ł. .............................................................................. 206

Major, R. .............................................................................. 206

Malakhov, Dmitri V. ............................................................... 53

Malyi, Oleksandr .................................................................. 221

Markström, A. ...................................................................... 172

Markus, Torsten ..................................................................... 31

Martial, Chantal .............................................................. 75;120

Masaki, Yoshihiro ................................................................ 219

Mascaro, Aurore .............................................................. 36;153

Masset, Patrick J. ....................................................... 72;74;195

Mathaudhu, Suveen .............................................................. 218

Matsumiya, Tooru .................................................................. 77

Mazères, B. ............................................................................ 67

McCalden, David ................................................................... 73

Medraj, Mamoun .................................................... 102;150;197

Mei Li ................................................................................... 165

Mei, Zhi-Gang ...................................................................... 108

Mentz, Juliane ........................................................................ 82

Mezbahul-Islam, Mohammad ....................................... 102;197

Miao Liu ............................................................................... 142

Michon, S. ............................................................................ 185

Mikula, A. ............................................................................ 109

Miranda, Hélio Cordeira de ................................................. 130

Mishra, Ratikant .............................................................. 89;137

Miyamoto, Takashi ............................................................... 202

Miyamoto, Y. ........................................................................ 219

Mohri, Tetsuo ......................................................................... 23

Monceau, D. ........................................................................... 67

Monteiro, M. ........................................................................ 171

Moreira, Marcelo F .............................................................. 180

Morgan, Dane....................................................................... 156

Moser, Z. .............................................................................. 206

Motojima, K. ........................................................................ 179

Moura Neto, Carlos de ......................................................... 174

Müller, M. ............................................................................ 110

Muralidhar, Abhiram ............................................................ 119

Murari, Fábio Dian ............................................................... 121

Music, Denis .......................................................................... 31

NN.N. Zhao ............................................................................. 189

Nagarajan, K. ....................................................................... 148

Napolitano, R.E. ..................................................................... 61

Naraghi, Reza ......................................................................... 41

Nathalie, Dupin ...................................................................... 71

Neugebauer, Jörg .................................................................... 19

Ng, Man-Fai ......................................................................... 217

Nishitani, S.R. ................................................... 29;216;219;220

Noel, Henri ............................................................................. 65

Noh, Ji-Young ...................................................................... 212

Norgren, Susanne ................................................................... 84

Novakovic, R. ...................................................................... 155

Nunes, Carlos Angelo ................................................... 184;203

OOdén, Magnus ................................................................... 85;98

Ohno, Y. .......................................................................... 29;216

Ohnuma, Ikuo ................................................... 87;192;201;202

Ohshima, Tadashi ................................................................. 132

Oikawa, Katsunari ................................................................ 192

Omori, Toshihiro ................................................. 51;87;192;201

Ondrej, Benes ......................................................................... 71

Ozolins, Vidvuds .................................................................. 108

PPalm, M. ................................................................................. 44

Palumbo, Mauro .................................................. 37;52;106;144

Park, Dong-Jun ...................................................................... 66

Park, Jeong-Yong ................................................................... 66

Park, Joo Hyun ....................................................................... 90

Park, Sang-Yoon .................................................................... 66

Pavlů, Jana ........................................................................ 24;25

Peisheng Wang ..................................................................... 163

Pekka, Taskinen ................................................................... 159

Peng Zhou .............................................................................. 50

Penin, Nicolas ........................................................................ 42

Pessoa, E.C.P. ....................................................................... 171

Petrilli, Helena Maria ............................................... 20;214;215

Petronela, Gotcu ..................................................................... 71

Petyuch, V. ........................................................................... 143

Phanon, D. .............................................................................. 42

Pinatel, E. R. ........................................................................ 144

232


Ping Wu ......................................................................... 217;221

Pinkas, Jiří ............................................................................ 227

Piron, Jean-Paul .............................................................. 75;120

Polishuk, Ilya ....................................................................... 213

Povoden-Karadeniz, E. ..................................................... 47;49

Prasad, B.S. Srinivas ............................................................ 178

Prostakova, Viktoria ............................................................... 93

Prymak, O. ............................................................................. 44

Pstrus, Janusz ......................................................... 190;199;204

QQin, G.W. ............................................................................. 189

Qing Chen ......................................................................... 38;86

RRaepsaet , Caroline .............................................................. 153

Rajkumar, V.B. .............................................................. 178;181

Ramirez, Antonio J ............................................................... 118

Rao, P.R. Vasudeva ....................................................... 148;191

Reddy, B. Prabhakara ........................................................... 148

Reed, Roger C ................................................................... 45;95

Reis, Danieli A. P. ................................................................ 174

Ribeiro, Shimeni Baptista .................................................... 126

Rizzi, P. ................................................................................ 144

Rizzo, F. ........................................................................ 170;171

Robelin, Christian ............................................................. 91;92

Rogl, Peter Franz .............................................................. 63;65

Romanowska, Jolanta .......................................................... 224

Romero, Sergio Antonio ...................................................... 180

SS.H. Liu ................................................................................ 172

Sabóia, Fernando Henrique Costa ........................................ 130

Sanchez, J.M. ......................................................................... 18

Sankaran, S. ......................................................................... 181

Santos, V.R ........................................................................... 171

Schaffnit, Philippe .................................................................. 82

Schmid-Fetzer, Rainer ......................................................... 101

Schneider, André .................................................................... 78

Schön, Cláudio G. ................................................................ 151

Schon, Claudio Geraldo .................................................. 20;215

Schon, Cláudio Geraldo ....................................................... 209

Schweitzer, Th. ..................................................................... 128

Seifert, Hans J ........................................................................ 57

Selleby, Malin ....................................................... 38;41;83;139

Senlin Cui............................................................................... 50

Shang, ShunLi ............................................................... 168;218

Shemet, V. ............................................................................ 143

Shevchenko, M.O. ......................................................... 157;158

Shihuai Zhou .......................................................................... 61

Shimenouchi, Shota ........................................................ 87;201

Shinagawa, Kazuya .............................................................. 192

Shishin, Denis ........................................................................ 99

Shuhong Liu ........................................................................... 62

Shun-Kang Pan .................................................................... 162

Sicheng Chen ....................................................................... 141

Silva, A. Costa e ............................................................ 170;171

Silva, Andre Luiz Vasconcelos da Costa e ............. 121;123;127

Silva, Carlos Antônio da ...................................................... 123

Silva, Eduardo Granado Monteiro da .................................. 200

Sippola, Hannu ..................................................................... 223

Siqueira, Rogério Navarro Correia de ................................. 131

Šob, M. ................................................................................... 25

Sodré, Ney .............................................................................. 20

Sola, Julio ............................................................................. 177

Sopousek, Jiří ................................................................ 226;227

Souaillat, Elise ....................................................................... 55

Souza, Eduardo Netto de ...................................................... 125

Staicu, D. ................................................................................ 68

Stein, F. .................................................................................. 44

Strandlund, Henrik ................................................................. 84

Su, Xuping .................................................................... 140;186

Sudavtsova, V.S. ............................................................ 157;158

Sugimoto, M. ....................................................................... 219

Sun, Lixian ............................................................................. 32

Sundman Bo .......................................................... 52;71;88;106

TTakao, Hisaaki ...................................................................... 132

Talekar, Anjali ................................................................... 27;42

Tanaka, Kouji ....................................................................... 132

Taniguchi, R. ........................................................................ 216

Tasnádi, Ferenc ............................................................ 28;85;98

Tédenac, Jean-Claude ............................................................ 22

Tedenac, Jean-Claude............................................................. 35

Teng, Lidong ........................................................................ 145

Toffolon-Masclet, Caroline ........................................ 36;67;153

Togase, K. .............................................................................. 29

Tokumoto, Y. .......................................................................... 29

Toro, Críspulo E. Deluque .............................................. 26;210

Tripathi, Nagendra ................................................................. 92

Turchi, Patrice E. A. ............................................................... 34

233


UUllbrand, Jennifer M. ........................................................ 85;98

Unfried S., Jimy ................................................................... 118

VVassilev, Georgui ................................................................. 198

Vébert, C. ............................................................................. 185

Velikanova, T. ...................................................................... 143

Vieira, Leandro Nakamura Alves .................................. 170;194

Viennois, Romain ................................................................... 22

Vilasi, Michel ................................................................ 184;203

Vilela, A. C. F. ...................................................................... 134

Villeger, P. ............................................................................ 128

Villela, Tales Ferreira .................................................... 184;203

Voß, S. .................................................................................... 44

Vřesťál, Jan ....................................................... 25;104;226;227

WW.Y. Wang ............................................................................ 218

Walle, A. van de ..................................................................... 21

Wang Fuming ....................................................................... 160

Wang Haitao ......................................................................... 160

Wanqi Jie ................................................................................ 50

Warczok, P. ............................................................................. 49

Warnken, Nils.................................................................... 45;95

Watson, Andy ....................................................................... 104

Wei Pan ................................................................................ 164

Wenqing Zhang ...................................................................... 62

XX.J. Liu..................................................................... 70;173;205

Xin Ren ................................................................................ 141

Xingqiu Chen ......................................................................... 63

Xiong, Wei ............................................................................. 38

Xu Fang ................................................................................ 161

YY.P. Ren ......................................................................... 103;189

Ya Liu ............................................................................ 140;186

Yamamoto, Yosuke ....................................................... 219;220

Yan Zhong ............................................................................ 162

Yang Bing............................................................................. 164

Yang Hongwei ...................................................................... 147

Yang Li ................................................................................... 31

Yaqoob, Khurram ................................................................. 193

Yijun Wang ............................................................ 147;168;218

Yingbiao Peng .......................................................... 62;163;164

Yiwei Li ................................................................................. 62

Yonenaga, I. .................................................................... 29;216

Yong Du ......................................32;50;62;97;161;163;164;172

Yu, Y. .................................................................................... 205

Yue Wu ................................................................................. 175

Yvon, Klaus ............................................................................ 42

ZZ.K. Liu ................................................................................ 218

Zabdyr, Leszek ..................................................................... 105

Zacherl, Chelsey .................................................................. 168

Zakulshi, W. ......................................................................... 207

Zelenaya, A. ......................................................................... 133

Zemanova, Adela ............................................ 104;137;138;226

Zhanpeng Jin ................................................................. 146;149

Zhenmin Du .............................................141;142;165;166;167

Zhong Chen ................................................................... 217;221

Zi-Kui Liu ........................................................... 30;32;108;168

234


List of Participants

Adela Zemanova [email protected] Czech

Adolf Mikula [email protected] Austria

Alan J. Ardell [email protected] Brazil

Ales Kroupa [email protected] Czech

Alexandre Bellegard Farina [email protected] Brazil

Alfredo Lúcio de Lima Figueiredo [email protected] Brazil

Aline Aguiar Lopes [email protected] Brazil

Anderson Willian de Souza Baltazar [email protected] Brazil

André Luiz Vasconcellos da Costa e Silva [email protected] Brazil

André Schneider [email protected] Germany

Andreas Markström [email protected] Sweden

Anjali Talekar [email protected] EUA

Annie Antoni-Zdziobek [email protected] France

Antonio José Ramirez Londoño [email protected] Brazil

Antonio Sergio Medeiros Fonseca [email protected] Brazil

Armando Fernández Guillermet [email protected] Argentine

Bengt Hallstedt [email protected] Germany

Benjamin Burton [email protected] USA

Bernd Böttger [email protected] Germany

Berthod Patrice [email protected] France

Biao Hu [email protected] China

Bo Jansson [email protected] Sweden

Bo Sundman [email protected] France

Bonnie Charlina Brusewitz Lindahl [email protected] Sweden

Byeong-Joo Lee [email protected] Korea

Catherine Colinet [email protected] France

Celso Luiz Moraes Alves [email protected] Brazil

Changrong Li [email protected] China

Chelsey L Zacherl [email protected] USA

Chonghe Li [email protected] China

Christian Robelin [email protected] Canada

Claudio Geraldo Schon [email protected] Brazil

Constantino Capurro [email protected] Brazil

Cuiping Guo [email protected] Germany

Cuiyun He [email protected] China

Dan Cai [email protected] China

Denis Shishin [email protected] Canada

Dhanesh Chandra [email protected] EUA

Dietmar Kobertz [email protected] Germany

235


Dmitri V. Malakhov [email protected] Canada

Dominika Jendrzejczyk- Handzlik [email protected] Poland

Ernst Kozeschnik [email protected] Austria

Erwin Povoden-Karadeniz [email protected] Austria

Eugenio Riccardo Pinatel [email protected] Italy

Fernando Cosme Rizzo Assunção [email protected] Brazil

Fiqiri Hodaj [email protected] France

Frank Stein [email protected] Germany

Fritz Körmann [email protected] Germany

Fuming Wang [email protected] China

Gilles Hug [email protected] France

Gueneau [email protected] France

Guilherme Antonio Defendi [email protected] Brazil

Guoxing Huang [email protected] China

Hamilton Porto Pimenta [email protected] Brazil

Hanchul Kim [email protected] Korea

Hang Wang [email protected] England

Hannu Sippola [email protected] Finland

Henrik Strandlund [email protected] Sweden

Herbert IPSER [email protected] Austria

Hongxiao LI [email protected] China

Humberto Luiz Gama de Magalhães [email protected] Brazil

Hyuck Mo Lee [email protected] Korea

Igor Abrikosov [email protected] Sweden

Iina Vaajamo [email protected] Finland

Ikuo Ohnuma [email protected] Japan

Ilya Polishuk [email protected] Israel

Ingee Kim [email protected] Korea

Jan Vrestal [email protected] Czech

Jana Pavlu [email protected] Czech

Janusz Pstrus [email protected] Poland

Jean Lehmann [email protected] France

Jean-Chrisophe Dumas [email protected] France

Jean-Claude Crivello [email protected] France

Jean-Claude Tedenac [email protected] France

Jean-Marc Joubert [email protected] France

Jee yong Lee [email protected] Korea

Jennifer M. Ullbrand [email protected] Sweden

Jimoh Sakiru Abiodun [email protected]

Ji-Young Noh [email protected] Korea

Joachim Konrad [email protected] Germany

John Ågren [email protected] Sweden

236


John Menichetti [email protected] EUA

Joohyun Park [email protected] Korea

Jörg Neugebauer [email protected] Germany

José Britti Bacalhau [email protected] Brazil

José Pablo Abriata [email protected] Argentine

Juan M. Sanchez [email protected] EUA

Julio Henrique Pimentel Medrano [email protected] Brazil

Kazuya Shinagawa [email protected] Japan

Khurram Yaqoob [email protected] France

Kiyohito Ishida [email protected] Japan

Krzysztof Fitzner [email protected] Poland

Lawrence P.Kaufman [email protected] USA

Leandro Nakamura Alves Vieira [email protected] Brazil

Libin Liu [email protected] China

Ligang Zhang [email protected] Germany

liling Jin [email protected] Canada

Luiz Tadeu Fernandes Eleno [email protected] Brazil

Malin Selleby [email protected] Sweden

Mamoun Medraj [email protected] Canada

Marc Duchesne [email protected] Canada

Marcelo Carboneri Carboni [email protected] Brazil

Markus Beilmann [email protected] Germany

Masanori Kajihara [email protected] Japan

Mauro Palumbo [email protected] Germany

Md Mezbahul Islam [email protected] Canada

Mehdi Hosseinifar [email protected] Canada

Meire Guimarães Lage [email protected] Brazil

Meis Constantin [email protected] France

Menahem Bamberger [email protected] Israel

Miao Liu [email protected] China

Min Jiang [email protected] China

Mohamed El Guendouzi [email protected] France

Nara Miranda Guimarães [email protected] Brazil

Nathalie Dupin [email protected] France

Nils Warnken [email protected] England

Olga Fabrichnaya [email protected] Germany

Ondrej Benes [email protected] Germany

Patrice E. A. Turchi [email protected] USA

Pavel Broz [email protected] Czech

Peng Zhou [email protected] China

Peter Rogl [email protected] Austria

Pierre Perrot [email protected] France

237


Przemyslaw Fima [email protected] Poland

Qing Chen [email protected] Sweden

Rainer Schmid-Fetzer [email protected] Germany

Reza Naraghi [email protected] Sweden

Ricardo Nolasco de Carvalho [email protected] Brazil

Roberto Ribeiro de Avillez [email protected] Brazil

Roney Eduardo Lino [email protected] Brazil

Ryo Taniguchi [email protected] Japan

Sergei A. Decterov [email protected] Canada

Shigeto R. Nishitani [email protected] Japan

Shihuai Zhou [email protected] USA

Shota Shimenouchi [email protected] Japan

Sung Hoon Lee [email protected] EUA

Susana Beatriz Ramos de Debiaggi [email protected] Brazil

Suzana G. Fries [email protected] Germany

Takashi Maeshima [email protected] Japan

Takashi Miyamoto [email protected] Japan

Tetsuo Mohri [email protected] Japan

Toffolon-Masclet Caroline [email protected] France

Tomas Gomez-Acebo [email protected] Spain

Tomasz Gancarz [email protected] Poland

Tooru Matsumiya [email protected] Japan

Torsten Markus [email protected] Germany

Ursula Kattner [email protected] USA

Vasily Lutsyk [email protected] Russia

Viktoria Prostakova [email protected] Canada

Wagner Viana Bielefeldt [email protected] Brazil

Wei Xiong [email protected] Sweden

Wladyslaw Gasior [email protected] Poland

Wojciech Zakulski [email protected] Poland

Yan Zhong [email protected] China

Yingbiao Peng [email protected] China

Yong Du [email protected] China

Yoshihiro Masaki [email protected] Japan

Yosuke Yamamoto [email protected] Japan

YU Yan [email protected] China

Yves Muggianu [email protected] France

Zabdyr Leszek [email protected] Poland

Zhenmin Du [email protected] China

Zi-Kui Liu [email protected] USA

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