summary of research by surreddi
Post on 26-Dec-2015
11 Views
Preview:
DESCRIPTION
TRANSCRIPT
Work carried out @
Chalmers, Sweden
Projects involved: Gear materials ---2010-12 NiTi Shape memory alloy ---2011-11 to 2012-06 VOLVO – low temperature creep --- 2011-11 to 2012-10 HIPERSINT Project --- 2012-07 to now INDUCTIONSINTERING --- 2013-04 to 2013-10 HÖGANÄS – Lit. review – XX steel --- 2013-01 Failure analysis – Borealis --- 2013-11 to 2013-12 KTH – JMatPro simulations –DOMEX --- 2013-10 to 2014-01 GKN-KME project --- 2014-01 to now
Activities: • Calibration of DSC (NETZSCH) • Atom Probe Tomography - Course attended • Poster – Materials for Tomorrow • Poster and demonstration – MPL opening • Poster – EuroPM2013 on NiTi shape memory alloy • Talk – EuroPM2013 on Low temperature Creep • Reviewer - JALCOM – 3 articles (total:9)
- Materials and Design – 1 article
Different microstructures but same composition
Finding critical feed rate
Manganese sulfide 20 40 60 0 A higher Bindex indicates better machinability
A Bindex of 100 represents the machinability of a free cutting steel
Ranking of materials by a Bindex
Chip morphology
TEM
Microstructure
Tool wear
Chip formation
Cutting forces
Build-up edge formation
Surface roughness
Machinability
80 100
Microstructure Machinability
Materials and Manufacturing Technology
FFI - Sustainable Gear Transmission Realization
Polar diagram - CLP
SEM material - CLP
SEM chip - CLP
Materials and Manufacturing Technology
TEM of a case hardening steel
Area Fe (At%) Cr (At%) Mn (At%)
All 96.76 1.63 1.75 A 86.60 7.08 6.72 B 93.43 4.34 2.22 C 100 0 0 D 86.29 7.57 6.13 E 98.75 0.73 0.57
A
B C
D
E
Coarse Lamellar Pearlite – Pearlite structure
Materials and Manufacturing Technology
Area Fe (At%) Cr (At%) Mn (At%)
All 96.04 1.97 1.99 A 82.48 12.37 5.15 B 83.45 10.93 5.62 C 97.43 1.11 1.46 D 96.67 1.35 1.98 E 81.96 11.41 6.63
A
B C D
E
Coarse Lamellar Pearlite – Precipitates
TEM of a case hardening steel
Ferrite microhardness in materials and chips
LNPm
at
SNPm
at
LNP0
5
LNP0
8
LNP1
SNP0
5
SNP0
8
SNP1
0
50
100
150
200
250
300
350
400
Micr
ohar
dnes
s HV
0.2
5
Microhardness results of chips can reveal strain hardening after machining. Microhardness results show higher hardness values at lower loads and following Meyer’s Law. The microhardness of chips is greater than the material due to high deformation. There is no clear trend in the chips of different feeds (feeds 0.05, 0.08 and 0.1mm/rev).
Material A Material B Material C Material D
Strain hardening at 25°C
0.1154 0.1183 0.1151 0.1134
at 600°C 0.1357 0.137 0.1336 0.1345
Strain hardening From the literature and data for 20MnCrS5, the strain hardening exponent: 0.11- 0.12 at RT Strain hardening depends on grain size and pearlite morphology According to JMatPro Considering 0.2% proof stress at 1e5 strain rate
the strain-hardening exponent n increases with increasing grain size in a certain range and decreases with increasing volume fraction of second phase for a given particle size*
* Zhang Fan et al., Materials Science and Engineering: A, Volume 122, Issue 2, 20 December 1989, Pages 211-213
XRD scan of NiTi gas atomized powder
XRD scan of starch consolidated and sintered sample
DSC scan of NiTi gas atomized powder
As Af
DSC scan of starch consolidated and sintered sample
As Af
Starch sintering As and Af shifted to higher temperature
Production of porous NiTi bulk shape memory alloy by starch consolidation and sintering
To produce porous samples by starch consolidation and sintering method using pre-alloyed NiTi powder for biomedical applications
NiTi - Starch consolidation and sintering
Blend
Mold
Consolidate (~75°C)
Freeze (‒20°C)
Demould
Dry
Green body Sinter in
argon (~1255°C)
• Production of samples: Starch consolidation and sintering, using experience from loose powder sintering.
• Evaluation of samples: • Porosity: Geom. and mass measurements. • Microstructure: XRD, DSC, OM, SEM and EDX. • Mechanical properties: Compression testing, cyclic loading
and microhardness tests.
Principle of starch consolidation
Slurry (left) with unconsolidated starch particles (white) and metal powder particles (grey) is heated to the consolidation temperature at which the starch consolidates
A demoulded and fully dried out sample next to its mould
EDM
NiTi – OM and SEM starch consolidation and sintering
Combined optical micrographs: porosity ~25
SEM images of starch sintered sample
SEM images of starch sintered sample. Various types of particles and phases were identified from EDX measurements: Fig a) shows the greyish areas which areTi4Ni2O or Ti2Ni Fig b) shows the dark particles which are TiC Fig c) shows Ni4Ti3 particles in NiTi matrix Fig d) shows large irregular particles which are Ni4Ti3 or Ni2Ti
Ø: 26 mm h: 8-10 mm
NiTi –starch consolidation and sintering Mechanical Properties
Residual strain: 2.1 % After anneal: 1.0 % Recovery: >50 %
Illustration of compression test samples by EDM from a sintered sample
Starch consolidated and sintered sample (polished)
Engineering stress-strain curves from compression test of a starch consolidated and sintered sample
Cyclic compression testing of a starch sintered sample
• sy > 1 GPa • su > 2 GPa • E > 25 GPa
Low Temperature Creep/Relaxation in PM Steels under Static Load
Water atomized iron powder prealloyed with Mo-1.5%
Alloying elements Ni-4% & Cu-2%
(diffusion bonded)
Diffusion alloyed powder grade from Höganäs AB
Samples Distaloy HP Denominations Description
1 DHP-UT Untempered 2 DHP-T200 Tempered at 200°C for 1 hour 3 DHP-T300 Tempered at 300°C for 1 hour
1
2
3
Material : Distaloy HP DHP-UT DHP-T200 DHP-T300
Tensile testing
Metallography
Austenite analysis by stress tech Xstress 3000
Hardness Apparent Hardness
Microhardness
Creep testing
Cyclic creep
1 million seconds ( ~ 277 hours)
Varying parameters
Instron universal testing machine with environmental chamber
Experimental Methods
14
Creep tests – 1 million seconds (~277 hours)
varying temperature
varying stress
Creep tests – with varying parameters
XRD : Master alloy Ni48Mn8B
HIPERSINT Code Description Density g/cc 3A - X-Astaloy 0,45Mo + 2,5%MA-20µm + 0,3%C-UF4 + 0,4%LubeE 7.1 and 7.3 3B - X-Astaloy 0,45Mo + 2,5%MA-45µm + 0,3%C-UF4 + 0,4%LubeE 7.1 and 7.3 4A - X-Astaloy 0,2Mo + 2,5%MA-20µm + 0,3%C-UF4 + 0,4%LubeE 7.1 and 7.3 4B - X-Astaloy 0,2Mo + 2,5%MA-45µm + 0,3%C-UF4 + 0,4%LubeE 7.1 and 7.3
Effect of MA particle size
Effect of Mo content
Effect of density
HIPERSINT - Dilatometry
18
Astaloy CrA 20µm MA Density 7.1
Spectrum Label
B Cr Mn Fe Ni Total
Spectrum 1 13.12 5.19 1.35 80.34 100.00 Spectrum 2 1.85 1.07 96.19 0.89 100.00 Spectrum 3 3.11 1.19 94.76 0.93 100.00 Spectrum 4 12.62 4.56 1.33 81.49 100.00 Spectrum 5 1.76 1.18 95.91 1.16 100.00 Spectrum 6 1.87 1.09 95.98 1.07 100.00 Spectrum 7 13.26 5.31 1.47 79.96 100.00 Spectrum 8 12.38 4.47 1.48 81.66 100.00 Spectrum 9 1.85 1.40 95.41 1.34 100.00 Spectrum 10 1.74 1.55 95.30 1.41 100.00
HIPERSINT
19
X-Astaloy0.2Mo 45µm MA
Density 7.1
Density 7.3
HIPERSINT
8th International Symposium on Superalloy 718 and Derivatives September 28-October 1, 2014 Marriott City Center • Pittsburgh, Pennsylvania
22
Work carried out during Ph.D @ IFW Dresden
• Mechanical alloying - Al-Y-Co-Ni (from elemental powders)
• Mechanical milling - Al-Y-Ni-Co - Al-Ni-La (melt spun ribbons) • Consolidation by HP and SPS - Al-Y-Ni-Co and composites (from milling) - Al-Y-Ni-Co - Al-Ni-La Gas atomized powders - Al-Gd-Ni-Co - Al-Nd-Ni-Co
• Spray deposits - Al-Y-Ni-Co - Al-Si Characterization and mech. properties - Al-Y-Ni-La-Co
• BMG ductilization - Vitreloy1 - Vitreloy 105 preparation, characterization, - Zr-Ti-Ag-Cu-Ni-Al mech. properties, surface modifications • Quasicrystals - Al-Cu-Fe • Laves phases - Fe-Zr, Fe-Zr-Cr • Crystallization kinetics - Al-Y-Ni-Co and Al-Gd-Ni-Co
23
XRD
• GAP : Amorphous
• 1st DSC peak : Amorphous fcc Al
• 2nd DSC peak : Amorphous
fcc Al + Al19Gd3Ni5 and Al9Co2
SEM
XRD (Co-Kα) Viscosity (10 K/min)
Viscosity
• viscous drop at Tg due to
super cooled liquid
Source : Ames Laboratory, Ames (USA) Size : d0.5 ~20 µm Morphology : smooth, round & satellites (< 1 µm) Microstructure: mostly featureless, large particles with crystallites
DSC (40 K/min)
DSC
• clear glass transition region
• two exothermic events
Al84Gd6Ni7Co3 Gas atomized powder
24
Al84Gd6Ni7Co3 – Crystallization kinetics
• activation energy (Ea) by the Kissinger method
• • Johnson-Mehl-Avrami
equation • .
• .
• .
[ ]( )nT tKtX )(exp1)( τ−−−=
−=
RTEKK A
T exp0
)ln(ln1
1lnln τ−+=
−tnKn
X T
Avrami exponent n can vary from 1 to 4 the transformation mechanism, such as the nucleation and growth behavior > 2.5 - increasing nucleation rate of all shapes; 2.5 - constant nucleation rate; 1.5-2.5 - decreasing
nucleation rate; 1.5 - zero nucleation rate; 1- needles and plates and thickening of long needles
25 1/6/2011 Surreddi-PhD defense
Al84Gd6Ni7Co3 – hot pressing Hot pressing at 573 K
at 623 K
at 673 K
at 723 K
26
Strength level similar to Zr- and Ti-based metallic glasses (but with strain hardening) Strength 3 times higher than high-strength conventional Al-based alloys High-strength combined with good plasticity due to UFG/nc Al and nc intermetallic compounds Best combination of strength and plastic strain for hot pressing at 673 K (full densification + retaining nano-sized microstructure)
HP Temperature
(K)
Yield stress σy (MPa)
Fracture stress
σf (MPa)
Fracture strain εf (%)
573 -- -- -- 623 -- 700 -- 673 1250 1560 3.5 723 1150 1440 4 773 900 1280 5.5
Ext-723 K 800 1130 3
Compression testing : • Instron 5869 testing facility • Compression test samples : 3 mm diameter and 6 mm length
RT compression test; strain rate 1× 10-4
Mechanical Properties
27
DSC:
No visible glass transition
2 exothermic events
Viscosity:
2 distinct viscosity drops
XRD:
As-atomized microstructure
: amorphous + fcc-Al
1st DSC peak : formation of fcc-Al
2nd DSC peak : formation of Al11La3 + Al3Ni
XRD (Co-Kα) DSC (40 K/min) (inset - Viscosity (10 K/min))
Gas atomized Al87Ni8La5 alloy powder
SPS at 713 K
28
Dark areas between particles - fcc-Al Bright particles - nanosized Al3Ni and Al11La3
Network of ultra fine-grained (UFG) Al reinforced with nm-scale intermetallic particles
Bright layers at the particles interface good densification efficient bonding
SPS sample sintered at 713 K
SPS - Al87Ni8La5 alloy
500nm 100 nm
SPS - Al87Ni8La5 alloy
30
0 5 10 15 20 25 300
200
400
600
800
1000
SPS 713 K
SPS 643 K
True
stre
ss (M
Pa)
True strain (%)
SPS 573 K
550 600 650 700280285290295300305310315320
Sintering temperature (K)H
ardn
ess (
HV)
920
940
960
980
1000
1020
1040
Maxim
um stress (M
Pa)
() Hardness () Maximum stress
With increasing sintering temperature • hardness decreases • maximum stress decreases Grain growth
Compressive strength: 900 – 1000 MPa Plastic strain: 10 – 25 % The fcc Al within the structure, are not confined and the continuous network of fcc Al allow the movement of dislocations, explaining the remarkable plastic deformation
RT compression test; strain rate 1× 10-4
Mechanical properties
Al-based metal matrix composites (MMCs) by powder metallurgy good microstructure control (volume fraction, size and morphology)
tunable mechanical properties good matrix – reinforcement interface low processing temperature
Matrices: pure Al and Al-based alloys
Reinforcements: metallic glasses (high strength 1 - 2 GPa, large elastic strain 1 - 2 % …) complex metallic alloys (CMAs) (high strength to weight ratio, HT strength ...)
quasicrystals (QCs) (high hardness, compatible thermal expansion coefficient …)
Processing route 1) reinforcement production by mechanical alloying/milling 2) matrix - reinforcement mixing 3) consolidation by hot pressing - hot extrusion
Al-based metal matrix composites (MMCs)
Pure Al + BM Al85Y8Ni5Co2 glassy ribbons (30 and 50 vol.%)
Glass-reinforced Al-based MMCs
XRD (Co-Kα)
DSC (40 K/min) Viscosity (10 K/min)
Rel. Density
Pure Al + BM Al85Y8Ni5Co2 glassy ribbons (30 and 50 vol.%)
Glass-reinforced Al-based MMCs
Scudino et al., J. Mater. Sci. 43 (2008) 4518
Al-based glassy flakes effective reinforcement strength 1.5 − 2 times higher than pure Al combined with good plastic deformation
BUT reinforcement production is very complex
RT compression tests
Spray Deposition - Al83La5Y5Ni5Co2
deposit and substrate
SEM micrographs of deposit OM micrographs of deposit
Laves phases and in situ LP composites
Fe90−xZr10Crx alloys (x = 0, 5 and 10) containing cubic C15 and hexagonal C14/C36 Laves phases in an ultrafine eutectic matrix of α-Fe
Laves phases and in situ LP composites
As-cast Fe80Zr10Cr10 rods with different mold diameter (Φ = 1, 2, 3 and 4 mm)
(a) Φ = 2 mm diameter (b) Φ = 1 mm diameter As-cast 4 mm diameter Fe80Zr10Cr10 rod
37
Metallic Glasses have amorphous structure, with short range order (< 1-2 nm)
Bulk means: 3D sample size not less than 0.5-1 mm in any dimension
Empirical rules of Glass Forming ability (GFA)
Multi-component alloy system
Atomic size difference above 12%
Negative heat of mixing among contituent elements
Tg/Tm > 2/3 deep eutectic high cooling rates to supress crystallization
• pure metals 1010 – 1012 K s−1
• binary alloys 104 – 106 K s−1
• multicomponent alloys 102 K s−1 or less
Metallic Glasses and Glass Formation ability
38
Copper Mold Casting
Melt Spinning
Planetary Ball Mill
Hot Pressing
Compacted Samples
Cast Samples Master Alloy
Amorphous and glassy materials preparation
BMG preparation
39
Bulk metallic glasses
Merits of metallic glasses:
unique properties / combinations
High hardness/ strength/elastic strain Corrosion and wear resistance
Drawbacks of metallic glasses
No classical work hardening
Brittle at room temperature
Localized deformation by shear banding
Possible ways to solve
Heterogeneous microstructure
Different scale / morphology
Casting, powder metallurgy
40
USB flash drive casing Products from BMG Schroers lab – Yale University
Apple’s iphone SIM card ejection tool
Swatch Group watch parts Golf clubs
Applications from Liquid metal technologies
Blow molding
Bulk metallic glasses - Ductilization
• designed-heterogeneities
BMG - cold-rolling Zr52.5Ti5Cu18Ni14.5Al10
Cu47.5Zr47.5Al5
BMG- frictional-boundary-restraints
Zr41.2Ti13.8Cu12.5Ni10Be22.5
BMG - channel-die-compression
@ Chalmers, Sweden
HR-SEM TEM XPS
Instron 5500R with 4505 load frame with Instron 3119-407
environment chamber
• Optical microscopy - Zeiss • Microhardness - Shimadzu • XRD – Bruker D8 • Stress tech – X3000 • STA 449 F1 and DIL 402C
@ IFW Dresden, Germany
Hot Press and Extrusion
Centrifugal casting Melt spinning Drop casting
Planetary ball mill Perkin Elmer DSC
• Arc melting • Nanoindentation • Microhardness • Instron 5869 • Modulus – Ultrasonic • Viscocity - DMA
top related