research article effect of nd addition on the microstructure and...
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Research ArticleEffect of Nd Addition on the Microstructure and MartensiticTransformation of Ni-Ti Shape Memory Alloys
M Dovchinvanchig12 C W Zhao1 S L Zhao1 X K Meng1 Y J Jin1 and Y M Xing1
1 College of Science Inner Mongolia University of Technology Hohhot 010051 China2 Institute of Physics and Technology Mongolian Academy of Sciences 210351 Ulaanbaatar Mongolia
Correspondence should be addressed to C W Zhao cwzhaoaliyuncom
Received 19 February 2014 Revised 18 April 2014 Accepted 2 May 2014 Published 20 May 2014
Academic Editor Shuichi Miyazaki
Copyright copy 2014 M Dovchinvanchig et al This is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited
The effect of rare earth element Nd addition on the microstructure and martensitic transformation behavior of Ni50Ti50minusxNdx
(119909 = 0 1 3 7 20) shape memory alloy was investigated experimentally The results showed that the microstructure of Ni-Ti-Ndternary alloy consists of the NiNd phase and the NiTi matrix One-step martensitic transformation was observed in all alloys Themartensitic transformation start temperature119872
119904increased gradually with increasing Nd content for Ni-Ti-Nd alloys
1 Introduction
Ni-Ti based shape memory alloys (SMAs) have uniqueshape memory effects and super-elasticity behavior and havebeen used in various fields particularly in engineering andmedical applications [1] Current research interest on SMAsmainly lies in controlling the martensitic transformationtemperature and improving the shapememory effect for theirapplicationsThe effects ofmartensitic transformation super-elasticity and shape memory have been widely studied byadding transitional elements to Ni-Ti binary alloys Theseelements include Fe [2] Hf [3] and Pd [4] It is foundthat most alloying elements such as Fe lower martensitictransformation temperature but there are only a few suchas Hf and Pd which increase martensitic transformationtemperature [5]
Moreover the microstructure and martensitic transfor-mation temperature of the rare earth (RE) of Ce [6] Gd[7] Dy [8] and La [9] in addition to Ni-Ti binary alloyshave also been studied using scanning electron microscopy(SEM) energy dispersive spectrometry (EDS) X-ray diffrac-tion (XRD) and differential scanning calorimetry (DSC)The addition of these REs to Ni-Ti binary alloys was foundto increase the martensitic transformation temperature andchange the phase transformation sequence
RE element Nd is also a widely used element particularlyin magnetic materials However only few studies have beenconducted on Nd addition to shape memory alloy The onlystudy found in the literature is that on Nd addition to Ni-Ti-Fe alloy but the Nd fraction is less than 1 at [10] Theeffect of Nd addition to Ni-Ti binary alloy on microstructureand martensite transformation temperature remains unclearIn this paper Nd content with atomic fractions of 1 37 and 20 was added to Ni-Ti binary alloys and themicrostructure and martensitic transformation were studiedexperimentally
2 Material and Methods
The Ni50Ti50minus119909
Nd119909alloys were prepared by melting each
10 g of raw materials with different nominal compositions(999 mass sponge Ti 997 mass electrolytic Ni and9995 mass Nd) in a nonconsumable arc-melting furnaceusing a water-cooled copper crucible The alloys are denotedby Nd0 Nd1 Nd3 Nd7 and Nd20 to refer to Ni
50Ti50
Ni50Ti49Nd1 Ni50Ti47Nd3 Ni50Ti43Nd7 and Ni
50Ti30Nd20
alloys respectively Arc-melting was repeated four times toensure the uniformity of composition The specimens arespark-cut from the ingots and solution-treated at 850∘C foran hour in a quartz tube furnace Subsequently the specimens
Hindawi Publishing CorporationAdvances in Materials Science and EngineeringVolume 2014 Article ID 489701 6 pageshttpdxdoiorg1011552014489701
2 Advances in Materials Science and Engineering
Table 1 Lattice parameters of Ni-Ti-Nd alloys
Alloy Phase 119886 (nm3) 119887 (nm3) 119888 (nm3) 120573 (∘) 119881 (nm3) SourceNd0 M 02898 04121 04619 9786 005464
This work
Nd1 M 02904 04123 04920 9811 005475A 03009 002724
Nd3 M 02939 04124 04639 9839 005562A 03017 002747
Nd7 M 02940 04136 04650 9925 005579A 03021 002757
Nd20 M 02948 04170 04657 9948 005645A 03026 002771
NiTiM 02898 04108 04646 9778 005480
JCPDF cardnumber65-0145
A 03007 002719JCPDF cardnumber65-4572
NiTi2 1131 14503JCPDF cardnumber72-0442
NiNd 03803 1046 04339 017262JCPDF cardnumber19-0818
were quenched using water Thereafter the specimens aremechanically and lightly polished to obtain a plain surface
The phase transformation temperatures of Ni50Ti50minus119909
Nd119909
alloys were determined by DSC using a TA Q2000 calorime-ter The temperature range of heating and cooling was fromminus30∘C to 140∘C and the scanning rate of heating and coolingwas 10∘Cmin SEM observations were conducted using aFEI Quanta 650 FEG equipped with EDS analysis systemsmade by Oxford An XRD experiment was conducted usinga DMAX-2500PC X-ray diffractometer The transmissionelectron microscope (TEM) sample was prepared using thestandard technique involving mechanical grinding followedby Ar+ ion milling TEM experiment was conducted on aJEM-2010 TEM at 200 kV Images were recorded on a Gatan1ktimes1k slow scan CCD camera and processed using the GatanDigitalMicrograph software
3 Results and Discussion
31 Microstructure of Ni50Ti50minus119909
Nd119909Alloy Figure 1(a) de-
picts the XRD curves of Ni50Ti50minus119909
Nd119909(119909 = 0 1 3 7 20)
alloys at room temperature The diffraction peaks are identi-fied to be from NiTi B191015840 martensite phase NiTi B2 austenitephase NiTi
2phase and NiNd alloy after comparing with
JCPDF cards (numbers 65-0145 65-4572 72-0442 and 19-0818) The detailed crystal plane indices are marked inFigure 1(b) for Nd0 and Figure 1(c) for Nd3 but the relativeintensities of each XRD curve are quite different because ofthe differences in martensite phase fraction and austenitephase fraction In this paper the letter M denotes the NiTiB191015840 martensite phase and the letter A denotes the NiTi B2austenite phase This perspective will be confirmed in the
following DSC analysis Figure 1(d) depicts a comparison of(111)M diffraction peaks of Ni
50Ti50minusxNdx(119909 = 0 1 3 7 20)
alloys The (111)M peak is observed to move toward theleft for Ni
50Ti50minusxNdx(119909 = 1 3 7 20) alloys that is the
diffraction angle decreases with increasing Nd fractionwhich indicates that the interplanar spacing of (111) of themartensite expands with Nd addition from 1 at to 20 atThe lattice parameters of alloys can be also calculated bypeaksrsquo position in XRD curves and shown in Table 1 It isshown clearly that the cell volume 119881 expands for eithermartensite or austenite withNd addition toNi-Ti binary alloyfrom 0 at to 20 atThe observation can also be confirmedin the following composition analysis
32 Morphologies and Compositions of Ni50Ti50minus119909
Nd119909
Alloys Figure 2 depicts the backscattering SEM images ofNi50Ti50minusxNdx (119909 = 0 1 3 7 20) alloys For Nd0 alloy
there are two different morphologies namely black phaseand matrix which can be identified in the SEM image(Figure 2(a)) The black phase is in irregular shape anddistributed randomly in the matrix For Nd1 Nd3 and Nd7two different morphologies namely white phase and matrixcan be identified in the SEM images (Figures 2(b)ndash2(d))Some white particles that are nearly round-shape and upto 4 120583m 6 120583m and 11 120583m in diameter respectively withwhite curving areas can be found to be distributed randomlyin the matrix When the Nd content is 20 at the whitephase mainly takes on very irregular shape and becomeslarger and interconnected while some white particles thatare nearly round-shaped and up to 14 120583m are also foundto be distributed in the matrix in Figure 2(e) The size ofthe white particles evidently increases whereas the white
Advances in Materials Science and Engineering 3
x = 20
x = 7
x = 3
x = 1
x = 0
Inte
nsity
2120579 (deg)20 30 40 50 60 70 80 90 100
NiTiMNiNd
NiTiA
(a)
2120579 (deg)20 30 40 50 60 70 80 90
3000
2500
2000
1500
1000
500
0
Inte
nsity
(cps
)
(100
)(minus101)
(110
)(422
)(002
)(minus111)
(511
)(020
)(111
)(440
)(minus112)
(112
)
(minus103)
(822
)
(minus131)
(131
)
(212
)
lowast
lowast
lowast
(422
)
lowast
lowast
NiTi2lowast
NiTiM
(b)
(021
)
2120579 (deg)20
0
30 40 50 60 70 80 90
1500
1000
500
Inte
nsity
(cps
)
NiTiMNiNd
NiTiA
(100) M
(minus101) M
(minus111) M
(020) M
(110) A
(111) M
(minus112) M
(132
)(112) M
(200) A
(211) A
(131) M
(212) M
(c)
Inte
nsity
2120579 (deg)44 45 46 47
(111)Mx = 20
x = 7
x = 3
x = 1
x = 0
(d)
Figure 1 XRD curves of Ni50Ti50minusxNdx alloys (a) XRD curves of Ni
50Ti50minusxNdx alloys (b) indexed diffraction peaks in Nd0 (c) indexed
diffraction peaks in Nd3 (d) comparison of (111)M diffraction peaks of Ni50Ti50minusxNdx alloys
phase overspreads steadily on the matrix with increasing Ndfraction
To identify the boundaries between the white phase andthe matrix TEM observation was conducted for Nd1 alloyand the TEM bright field images of a small nearly round-shaped particle with a diameter of 17120583m and a large nearlyround-shaped particle with a diameter of 36120583mare shown inFigure 3The boundaries between these two particles and thematrix look very bright and can be identified clearly at sucha very low magnification which means that the boundariesare incoherent Furthermore Xu et al proposed that thebinding force of RE elements and Ni is much bigger thanthat of Ni and Ti [11] So NiNd phase is formed first andthen NiTi phase crystallization occurs during the Ni-Ti-Ndalloys preparation Thus NiNd phase and NiTi matrix haveno orientation relationship [5]
To identify the phase structure EDS analysis was con-ducted in SEM The compositions of Ni-Ti-Nd alloys are
shown in Table 2 The Ti Ni ratio in the matrix of all Ni-Ti-Nd alloys is measured to be near 1 Thus the matrix can beconcluded to beNiTi phase with a small amount of Nd soluteTheTi Ni ratio in the black phase of Nd0 alloy ismeasured tobe near 2 1 By XRD analysis there is a NiTi
2phase in Nd0
Thus the black phase can be concluded to be NiTi2phase
According to the 773K isothermal section of the ternary alloyphase diagram of the Ni-Ti-Nd no intermetallic compoundscan be found in the Ti-Nd binary system However Ni-Ndbinary alloy phase diagram shows seven kinds of intermetalliccompounds defined as NdNi
5 Nd2Ni7 NdNi
3 NdNi
2 NdNi
Nd7Ni13 and Nd
3Ni [12] The EDS results show that the
Ni Nd ratio in the white phase is near 1 and can be regardedas the NiNd intermetallic compound with a small amount ofTi solute The amount and size of the NiNd phase increasewith increasing Nd fraction (Figure 2)
Furthermore Nd content has also been found in thematrix of Nd3 Nd7 and Nd20 The Nd atomic radius(0206 nm) is known to be larger than Ti atomic radius
4 Advances in Materials Science and Engineering
Ni50Ti50(a)
(a)
Ni50Ti49Nd1(b)
(b)
Ni50Ti47Nd3(c)
(c)
Ni50Ti43Nd7(d)
(d)
Ni50Ti30Nd20(e)
(e)
Figure 2 Back-scattering SEM images of Ni50Ti50minusxNdx alloys (a) Ni
50Ti50 (b) Ni
50Ti49Nd1 (c) Ni
50Ti47Nd3 (d) Ni
50Ti43Nd7 (e)
Ni50Ti30Nd20
(a) (b)
Figure 3 TEM bright field images of Ni50Ti49Nd1alloy (a) small particle (b) large particle
Advances in Materials Science and Engineering 5
Hea
t flow
x = 20
x = 7
x = 3
x = 1
x = 0
Cooling
Heating
Temperature (∘C)0 40 80 120
(a)
Tem
pera
ture
(∘C)
Nd concentration (at )0 5 10 15 20
80
60
40
20
0
minus20
minus40
minus60
Ni50Ti50minusxNdx
Nd0Ni507Ti493 [7]
Ni50Ti50 [14]Ni498Ti502 [15]
(b)
Figure 4 DSC curve and martensite transformation temperature of Ni50Ti50minus119909
Nd119909alloys (a) DSC curves (b)119872
119904curve
(0176 nm) by 17 and Ni atomic radius (0149 nm) by 38[13] The Nd atom occupies the position of Ni or Ti conse-quentially resulting in an expansion of the NiTi matrix lattice[7] which is consistent with the previous XRD analysis
33 Phase Transformation of Ni50Ti50minus119909
Nd119909
AlloysFigure 4(a) depicts theDSC curves of theNi
50Ti50minus119909
Nd119909(119909 =
0 1 3 7 20) alloys Each DSC curve of Nd0 Nd1 Nd3 Nd7and Nd20 shows only one peak during the heating andcooling process which indicates a one-step B2harrB191015840phase transformation Figure 4(b) shows the effect ofNd concentration on martensitic transformation starttemperature 119872
119904 For Nd0 alloy the 119872
119904is measured to
be 7744∘C It is well known that quenched Ni-Ti binaryalloys show one-step B2harrB191015840 transformation and thetransformation temperatures are strongly dependent on Niconcentration [5 7] 01 at increase in Ni concentrationcan lower the119872
119904of Ni-Ti binary alloys by more than 10∘C
For example Liu et al measured the119872119904to be about minus50∘C
for Ni507
Ti493
alloy after annealing at 900∘C for 60min [7]Tabish et al measured the 119872
119904to be minus2212∘C for Ni
50Ti50
alloy after annealing at 1000∘C for 120min [14] Wasilewskiet al measured the119872
119904to be 65∘C for Ni
498Ti502
alloy [15] Inthis work the composition of the matrix in Nd0 is measuredto be Ni
4936Ti5064
which is Ti-rich So a high 119872119904of Ti-
Ni binary alloy Nd0 is reasonable Again the martensitetransformations finish temperature 119872
119891in Nd0 alloy is
higher than room temperature of 20∘C Thus the martensitetransformations have finished at room temperature and theNd0 alloy should be in total martensite phase which is inagreement with the XRD results
Meanwhile as shown in Figure 4 the119872119904increases with
increasing Nd fraction from 1 at to 20 at And all 119872119891
in four DSC curves of Nd addition alloys are lower thanroom temperature Thus martensite transformation cannot
Table 2 Compositions of Ni-Ti-Nd alloys
Ti (at) Ni (at) Nd (at)
Nd0 Matrix 5064 4936 mdashBlack phase 6699 3301 mdash
Nd1 Matrix 5061 4939 0White phase 555 4967 4478
Nd3 Matrix 4924 5021 055White phase 297 4984 4719
Nd7 Matrix 4999 4895 106White phase 431 4772 4797
Nd20 Matrix 4927 4899 174White phase 168 4978 4854
finish fully at room temperature which indicates that boththe austenite phase and the martensite phase exist in the Ni-Ti-Nd alloy For Nd1 alloy the119872
119891is higher than the others
afterwhich themartensite transformation has nearly finishedThus a higher martensite fraction than austenite fraction ispresent Consequently the XRD curve of Nd1 shows that theintensities of themartensite diffraction peaks are significantlyhigher than those of austenite in Figure 1(a) With increasingNd fraction the 119872
119891 the martensite fraction in the alloy
and the relative XRD intensities of the martensite diffractionpeaks also decreased
4 Conclusions
In summary the effect of RE element Nd addition on themicrostructure and martensitic transformation behavior wasinvestigated by XRD SEM TEM and DSC The microstruc-ture of the Ni
50Ti50minus119909
Nd119909alloys consists of NiNd alloy with
a small amount of Ti solute and NiTi matrix with a small
6 Advances in Materials Science and Engineering
amount of Nd solute The lattice of NiTi matrix is expandedbyNd additionTheNi-Ti-Nd alloy has a one-stepmartensitictransformation Increasing the Nd fraction the martensitictransformation start temperature119872
119904increases gradually
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgments
This work was supported by the National Natural ScienceFoundation of China (Grant no 51261017) the Program forNew Century Excellent Talents in University (Grant noNCET-10-0909) and the Specialized Research Fund forthe Doctoral Program of Higher Education (Grant no20101514110002)
References
[1] K Otsuka and X Ren ldquoRecent developments in the research ofshape memory alloysrdquo Intermetallics vol 7 no 5 pp 511ndash5281999
[2] J Frenzel J Pfetzing K Neuking andG Eggeler ldquoOn the influ-ence of thermomechanical treatments on the microstructureand phase transformation behavior of Ni-Ti-Fe shape memoryalloysrdquo Materials Science and Engineering A vol 482ndash484 no1-2 pp 635ndash638 2008
[3] X L Meng W Cai Y D Fu Q F Li J X Zhang and L CZhao ldquoShape-memory behaviors in an aged Ni-rich TiNiHfhigh temperature shape-memory alloyrdquo Intermetallics vol 16no 5 pp 698ndash705 2008
[4] Y LiuM Kohl K Okutsu and SMiyazaki ldquoA TiNiPd thin filmmicrovalve for high temperature applicationsrdquoMaterials Scienceand Engineering A vol 378 no 1-2 pp 205ndash209 2004
[5] K Otsuka and X Ren ldquoPhysical metallurgy of Ti-Ni-basedshape memory alloysrdquo Progress in Materials Science vol 50 no5 pp 511ndash678 2005
[6] W Cai A L Liu J H Sui and L C Zhao ldquoEffects of ceriumaddition on martensitic transformation and microstructure ofTi493
Ni507
alloyrdquoMaterials Transactions vol 47 no 3 pp 716ndash719 2006
[7] A L LiuW Cai Z Y Gao and L C Zhao ldquoThemicrostructureand martensitic transformation of (Ti
493Ni507
)1minus119909
Gd119909shape
memory alloysrdquoMaterials Science and Engineering A vol 438ndash440 pp 634ndash638 2006
[8] A L Liu Z Y Gao L Gao W Cai and Y Wu ldquoEffect of Dyaddition on the microstructure and martensitic transformationof a Ni-rich TiNi shape memory alloyrdquo Journal of Alloys andCompounds vol 437 no 1-2 pp 339ndash343 2007
[9] J W Xu A L Liu B Y Qian and W Cai ldquoInvestigation onmicrostructure and phase transformation of La added TiNishape memory alloyrdquo Advanced Materials Research vol 557ndash559 pp 1041ndash1044 2012
[10] J GWang and F S Liu ldquoPhase transformation andmicrostruc-ture of Ti
50Ni48minus119909
Fe2Nd119909shapememory alloysrdquoChinese Journal
of Aeronautics vol 22 no 3 pp 334ndash338 2009[11] J-WXu A-L Liu andWCai ldquoCrystal structure and formation
mechanism of rare earth rich phases in Ti-Ni-Ce alloysrdquo Journal
of Functional Materials vol 39 no 4 pp 600ndash602 2008 (Chi-nese)
[12] J Q Liu Y H Zhuang and Y Q Hu ldquoThe 773K isothermalsection of the ternary phase diagram of the Nd-Ni-Tirdquo Journalof Alloys and Compounds vol 368 no 1-2 pp 180ndash181 2004
[13] E Clementi D L Raimondi and W P Reinhardt ldquoAtomicscreening constants from SCF functions II Atoms with 37 to86 electronsrdquoThe Journal of Chemical Physics vol 47 no 4 pp1300ndash1307 1967
[14] T A Tabish S Atiq M Ali A N Ch Z U Reham and T ZButt ldquoDevelopment and characterization of Ni
50Ti50
shapememory alloy used for biomedical applicationsrdquo InternationalJournal of Chemical Materials Science and Engineering vol 7no 12 pp 92ndash93 2013
[15] R JWasilewski S R Butler and J EHanlon ldquoOn themartensi-tic transformation in TiNirdquo Metallurgical Transactions vol 1no 1 pp 104ndash110 1967
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Journal ofNanomaterials
2 Advances in Materials Science and Engineering
Table 1 Lattice parameters of Ni-Ti-Nd alloys
Alloy Phase 119886 (nm3) 119887 (nm3) 119888 (nm3) 120573 (∘) 119881 (nm3) SourceNd0 M 02898 04121 04619 9786 005464
This work
Nd1 M 02904 04123 04920 9811 005475A 03009 002724
Nd3 M 02939 04124 04639 9839 005562A 03017 002747
Nd7 M 02940 04136 04650 9925 005579A 03021 002757
Nd20 M 02948 04170 04657 9948 005645A 03026 002771
NiTiM 02898 04108 04646 9778 005480
JCPDF cardnumber65-0145
A 03007 002719JCPDF cardnumber65-4572
NiTi2 1131 14503JCPDF cardnumber72-0442
NiNd 03803 1046 04339 017262JCPDF cardnumber19-0818
were quenched using water Thereafter the specimens aremechanically and lightly polished to obtain a plain surface
The phase transformation temperatures of Ni50Ti50minus119909
Nd119909
alloys were determined by DSC using a TA Q2000 calorime-ter The temperature range of heating and cooling was fromminus30∘C to 140∘C and the scanning rate of heating and coolingwas 10∘Cmin SEM observations were conducted using aFEI Quanta 650 FEG equipped with EDS analysis systemsmade by Oxford An XRD experiment was conducted usinga DMAX-2500PC X-ray diffractometer The transmissionelectron microscope (TEM) sample was prepared using thestandard technique involving mechanical grinding followedby Ar+ ion milling TEM experiment was conducted on aJEM-2010 TEM at 200 kV Images were recorded on a Gatan1ktimes1k slow scan CCD camera and processed using the GatanDigitalMicrograph software
3 Results and Discussion
31 Microstructure of Ni50Ti50minus119909
Nd119909Alloy Figure 1(a) de-
picts the XRD curves of Ni50Ti50minus119909
Nd119909(119909 = 0 1 3 7 20)
alloys at room temperature The diffraction peaks are identi-fied to be from NiTi B191015840 martensite phase NiTi B2 austenitephase NiTi
2phase and NiNd alloy after comparing with
JCPDF cards (numbers 65-0145 65-4572 72-0442 and 19-0818) The detailed crystal plane indices are marked inFigure 1(b) for Nd0 and Figure 1(c) for Nd3 but the relativeintensities of each XRD curve are quite different because ofthe differences in martensite phase fraction and austenitephase fraction In this paper the letter M denotes the NiTiB191015840 martensite phase and the letter A denotes the NiTi B2austenite phase This perspective will be confirmed in the
following DSC analysis Figure 1(d) depicts a comparison of(111)M diffraction peaks of Ni
50Ti50minusxNdx(119909 = 0 1 3 7 20)
alloys The (111)M peak is observed to move toward theleft for Ni
50Ti50minusxNdx(119909 = 1 3 7 20) alloys that is the
diffraction angle decreases with increasing Nd fractionwhich indicates that the interplanar spacing of (111) of themartensite expands with Nd addition from 1 at to 20 atThe lattice parameters of alloys can be also calculated bypeaksrsquo position in XRD curves and shown in Table 1 It isshown clearly that the cell volume 119881 expands for eithermartensite or austenite withNd addition toNi-Ti binary alloyfrom 0 at to 20 atThe observation can also be confirmedin the following composition analysis
32 Morphologies and Compositions of Ni50Ti50minus119909
Nd119909
Alloys Figure 2 depicts the backscattering SEM images ofNi50Ti50minusxNdx (119909 = 0 1 3 7 20) alloys For Nd0 alloy
there are two different morphologies namely black phaseand matrix which can be identified in the SEM image(Figure 2(a)) The black phase is in irregular shape anddistributed randomly in the matrix For Nd1 Nd3 and Nd7two different morphologies namely white phase and matrixcan be identified in the SEM images (Figures 2(b)ndash2(d))Some white particles that are nearly round-shape and upto 4 120583m 6 120583m and 11 120583m in diameter respectively withwhite curving areas can be found to be distributed randomlyin the matrix When the Nd content is 20 at the whitephase mainly takes on very irregular shape and becomeslarger and interconnected while some white particles thatare nearly round-shaped and up to 14 120583m are also foundto be distributed in the matrix in Figure 2(e) The size ofthe white particles evidently increases whereas the white
Advances in Materials Science and Engineering 3
x = 20
x = 7
x = 3
x = 1
x = 0
Inte
nsity
2120579 (deg)20 30 40 50 60 70 80 90 100
NiTiMNiNd
NiTiA
(a)
2120579 (deg)20 30 40 50 60 70 80 90
3000
2500
2000
1500
1000
500
0
Inte
nsity
(cps
)
(100
)(minus101)
(110
)(422
)(002
)(minus111)
(511
)(020
)(111
)(440
)(minus112)
(112
)
(minus103)
(822
)
(minus131)
(131
)
(212
)
lowast
lowast
lowast
(422
)
lowast
lowast
NiTi2lowast
NiTiM
(b)
(021
)
2120579 (deg)20
0
30 40 50 60 70 80 90
1500
1000
500
Inte
nsity
(cps
)
NiTiMNiNd
NiTiA
(100) M
(minus101) M
(minus111) M
(020) M
(110) A
(111) M
(minus112) M
(132
)(112) M
(200) A
(211) A
(131) M
(212) M
(c)
Inte
nsity
2120579 (deg)44 45 46 47
(111)Mx = 20
x = 7
x = 3
x = 1
x = 0
(d)
Figure 1 XRD curves of Ni50Ti50minusxNdx alloys (a) XRD curves of Ni
50Ti50minusxNdx alloys (b) indexed diffraction peaks in Nd0 (c) indexed
diffraction peaks in Nd3 (d) comparison of (111)M diffraction peaks of Ni50Ti50minusxNdx alloys
phase overspreads steadily on the matrix with increasing Ndfraction
To identify the boundaries between the white phase andthe matrix TEM observation was conducted for Nd1 alloyand the TEM bright field images of a small nearly round-shaped particle with a diameter of 17120583m and a large nearlyround-shaped particle with a diameter of 36120583mare shown inFigure 3The boundaries between these two particles and thematrix look very bright and can be identified clearly at sucha very low magnification which means that the boundariesare incoherent Furthermore Xu et al proposed that thebinding force of RE elements and Ni is much bigger thanthat of Ni and Ti [11] So NiNd phase is formed first andthen NiTi phase crystallization occurs during the Ni-Ti-Ndalloys preparation Thus NiNd phase and NiTi matrix haveno orientation relationship [5]
To identify the phase structure EDS analysis was con-ducted in SEM The compositions of Ni-Ti-Nd alloys are
shown in Table 2 The Ti Ni ratio in the matrix of all Ni-Ti-Nd alloys is measured to be near 1 Thus the matrix can beconcluded to beNiTi phase with a small amount of Nd soluteTheTi Ni ratio in the black phase of Nd0 alloy ismeasured tobe near 2 1 By XRD analysis there is a NiTi
2phase in Nd0
Thus the black phase can be concluded to be NiTi2phase
According to the 773K isothermal section of the ternary alloyphase diagram of the Ni-Ti-Nd no intermetallic compoundscan be found in the Ti-Nd binary system However Ni-Ndbinary alloy phase diagram shows seven kinds of intermetalliccompounds defined as NdNi
5 Nd2Ni7 NdNi
3 NdNi
2 NdNi
Nd7Ni13 and Nd
3Ni [12] The EDS results show that the
Ni Nd ratio in the white phase is near 1 and can be regardedas the NiNd intermetallic compound with a small amount ofTi solute The amount and size of the NiNd phase increasewith increasing Nd fraction (Figure 2)
Furthermore Nd content has also been found in thematrix of Nd3 Nd7 and Nd20 The Nd atomic radius(0206 nm) is known to be larger than Ti atomic radius
4 Advances in Materials Science and Engineering
Ni50Ti50(a)
(a)
Ni50Ti49Nd1(b)
(b)
Ni50Ti47Nd3(c)
(c)
Ni50Ti43Nd7(d)
(d)
Ni50Ti30Nd20(e)
(e)
Figure 2 Back-scattering SEM images of Ni50Ti50minusxNdx alloys (a) Ni
50Ti50 (b) Ni
50Ti49Nd1 (c) Ni
50Ti47Nd3 (d) Ni
50Ti43Nd7 (e)
Ni50Ti30Nd20
(a) (b)
Figure 3 TEM bright field images of Ni50Ti49Nd1alloy (a) small particle (b) large particle
Advances in Materials Science and Engineering 5
Hea
t flow
x = 20
x = 7
x = 3
x = 1
x = 0
Cooling
Heating
Temperature (∘C)0 40 80 120
(a)
Tem
pera
ture
(∘C)
Nd concentration (at )0 5 10 15 20
80
60
40
20
0
minus20
minus40
minus60
Ni50Ti50minusxNdx
Nd0Ni507Ti493 [7]
Ni50Ti50 [14]Ni498Ti502 [15]
(b)
Figure 4 DSC curve and martensite transformation temperature of Ni50Ti50minus119909
Nd119909alloys (a) DSC curves (b)119872
119904curve
(0176 nm) by 17 and Ni atomic radius (0149 nm) by 38[13] The Nd atom occupies the position of Ni or Ti conse-quentially resulting in an expansion of the NiTi matrix lattice[7] which is consistent with the previous XRD analysis
33 Phase Transformation of Ni50Ti50minus119909
Nd119909
AlloysFigure 4(a) depicts theDSC curves of theNi
50Ti50minus119909
Nd119909(119909 =
0 1 3 7 20) alloys Each DSC curve of Nd0 Nd1 Nd3 Nd7and Nd20 shows only one peak during the heating andcooling process which indicates a one-step B2harrB191015840phase transformation Figure 4(b) shows the effect ofNd concentration on martensitic transformation starttemperature 119872
119904 For Nd0 alloy the 119872
119904is measured to
be 7744∘C It is well known that quenched Ni-Ti binaryalloys show one-step B2harrB191015840 transformation and thetransformation temperatures are strongly dependent on Niconcentration [5 7] 01 at increase in Ni concentrationcan lower the119872
119904of Ni-Ti binary alloys by more than 10∘C
For example Liu et al measured the119872119904to be about minus50∘C
for Ni507
Ti493
alloy after annealing at 900∘C for 60min [7]Tabish et al measured the 119872
119904to be minus2212∘C for Ni
50Ti50
alloy after annealing at 1000∘C for 120min [14] Wasilewskiet al measured the119872
119904to be 65∘C for Ni
498Ti502
alloy [15] Inthis work the composition of the matrix in Nd0 is measuredto be Ni
4936Ti5064
which is Ti-rich So a high 119872119904of Ti-
Ni binary alloy Nd0 is reasonable Again the martensitetransformations finish temperature 119872
119891in Nd0 alloy is
higher than room temperature of 20∘C Thus the martensitetransformations have finished at room temperature and theNd0 alloy should be in total martensite phase which is inagreement with the XRD results
Meanwhile as shown in Figure 4 the119872119904increases with
increasing Nd fraction from 1 at to 20 at And all 119872119891
in four DSC curves of Nd addition alloys are lower thanroom temperature Thus martensite transformation cannot
Table 2 Compositions of Ni-Ti-Nd alloys
Ti (at) Ni (at) Nd (at)
Nd0 Matrix 5064 4936 mdashBlack phase 6699 3301 mdash
Nd1 Matrix 5061 4939 0White phase 555 4967 4478
Nd3 Matrix 4924 5021 055White phase 297 4984 4719
Nd7 Matrix 4999 4895 106White phase 431 4772 4797
Nd20 Matrix 4927 4899 174White phase 168 4978 4854
finish fully at room temperature which indicates that boththe austenite phase and the martensite phase exist in the Ni-Ti-Nd alloy For Nd1 alloy the119872
119891is higher than the others
afterwhich themartensite transformation has nearly finishedThus a higher martensite fraction than austenite fraction ispresent Consequently the XRD curve of Nd1 shows that theintensities of themartensite diffraction peaks are significantlyhigher than those of austenite in Figure 1(a) With increasingNd fraction the 119872
119891 the martensite fraction in the alloy
and the relative XRD intensities of the martensite diffractionpeaks also decreased
4 Conclusions
In summary the effect of RE element Nd addition on themicrostructure and martensitic transformation behavior wasinvestigated by XRD SEM TEM and DSC The microstruc-ture of the Ni
50Ti50minus119909
Nd119909alloys consists of NiNd alloy with
a small amount of Ti solute and NiTi matrix with a small
6 Advances in Materials Science and Engineering
amount of Nd solute The lattice of NiTi matrix is expandedbyNd additionTheNi-Ti-Nd alloy has a one-stepmartensitictransformation Increasing the Nd fraction the martensitictransformation start temperature119872
119904increases gradually
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgments
This work was supported by the National Natural ScienceFoundation of China (Grant no 51261017) the Program forNew Century Excellent Talents in University (Grant noNCET-10-0909) and the Specialized Research Fund forthe Doctoral Program of Higher Education (Grant no20101514110002)
References
[1] K Otsuka and X Ren ldquoRecent developments in the research ofshape memory alloysrdquo Intermetallics vol 7 no 5 pp 511ndash5281999
[2] J Frenzel J Pfetzing K Neuking andG Eggeler ldquoOn the influ-ence of thermomechanical treatments on the microstructureand phase transformation behavior of Ni-Ti-Fe shape memoryalloysrdquo Materials Science and Engineering A vol 482ndash484 no1-2 pp 635ndash638 2008
[3] X L Meng W Cai Y D Fu Q F Li J X Zhang and L CZhao ldquoShape-memory behaviors in an aged Ni-rich TiNiHfhigh temperature shape-memory alloyrdquo Intermetallics vol 16no 5 pp 698ndash705 2008
[4] Y LiuM Kohl K Okutsu and SMiyazaki ldquoA TiNiPd thin filmmicrovalve for high temperature applicationsrdquoMaterials Scienceand Engineering A vol 378 no 1-2 pp 205ndash209 2004
[5] K Otsuka and X Ren ldquoPhysical metallurgy of Ti-Ni-basedshape memory alloysrdquo Progress in Materials Science vol 50 no5 pp 511ndash678 2005
[6] W Cai A L Liu J H Sui and L C Zhao ldquoEffects of ceriumaddition on martensitic transformation and microstructure ofTi493
Ni507
alloyrdquoMaterials Transactions vol 47 no 3 pp 716ndash719 2006
[7] A L LiuW Cai Z Y Gao and L C Zhao ldquoThemicrostructureand martensitic transformation of (Ti
493Ni507
)1minus119909
Gd119909shape
memory alloysrdquoMaterials Science and Engineering A vol 438ndash440 pp 634ndash638 2006
[8] A L Liu Z Y Gao L Gao W Cai and Y Wu ldquoEffect of Dyaddition on the microstructure and martensitic transformationof a Ni-rich TiNi shape memory alloyrdquo Journal of Alloys andCompounds vol 437 no 1-2 pp 339ndash343 2007
[9] J W Xu A L Liu B Y Qian and W Cai ldquoInvestigation onmicrostructure and phase transformation of La added TiNishape memory alloyrdquo Advanced Materials Research vol 557ndash559 pp 1041ndash1044 2012
[10] J GWang and F S Liu ldquoPhase transformation andmicrostruc-ture of Ti
50Ni48minus119909
Fe2Nd119909shapememory alloysrdquoChinese Journal
of Aeronautics vol 22 no 3 pp 334ndash338 2009[11] J-WXu A-L Liu andWCai ldquoCrystal structure and formation
mechanism of rare earth rich phases in Ti-Ni-Ce alloysrdquo Journal
of Functional Materials vol 39 no 4 pp 600ndash602 2008 (Chi-nese)
[12] J Q Liu Y H Zhuang and Y Q Hu ldquoThe 773K isothermalsection of the ternary phase diagram of the Nd-Ni-Tirdquo Journalof Alloys and Compounds vol 368 no 1-2 pp 180ndash181 2004
[13] E Clementi D L Raimondi and W P Reinhardt ldquoAtomicscreening constants from SCF functions II Atoms with 37 to86 electronsrdquoThe Journal of Chemical Physics vol 47 no 4 pp1300ndash1307 1967
[14] T A Tabish S Atiq M Ali A N Ch Z U Reham and T ZButt ldquoDevelopment and characterization of Ni
50Ti50
shapememory alloy used for biomedical applicationsrdquo InternationalJournal of Chemical Materials Science and Engineering vol 7no 12 pp 92ndash93 2013
[15] R JWasilewski S R Butler and J EHanlon ldquoOn themartensi-tic transformation in TiNirdquo Metallurgical Transactions vol 1no 1 pp 104ndash110 1967
Submit your manuscripts athttpwwwhindawicom
ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CorrosionInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Polymer ScienceInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CeramicsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CompositesJournal of
NanoparticlesJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
International Journal of
Biomaterials
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
NanoscienceJournal of
TextilesHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Journal of
NanotechnologyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
CrystallographyJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CoatingsJournal of
Advances in
Materials Science and EngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Smart Materials Research
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
MetallurgyJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
BioMed Research International
MaterialsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Nano
materials
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal ofNanomaterials
Advances in Materials Science and Engineering 3
x = 20
x = 7
x = 3
x = 1
x = 0
Inte
nsity
2120579 (deg)20 30 40 50 60 70 80 90 100
NiTiMNiNd
NiTiA
(a)
2120579 (deg)20 30 40 50 60 70 80 90
3000
2500
2000
1500
1000
500
0
Inte
nsity
(cps
)
(100
)(minus101)
(110
)(422
)(002
)(minus111)
(511
)(020
)(111
)(440
)(minus112)
(112
)
(minus103)
(822
)
(minus131)
(131
)
(212
)
lowast
lowast
lowast
(422
)
lowast
lowast
NiTi2lowast
NiTiM
(b)
(021
)
2120579 (deg)20
0
30 40 50 60 70 80 90
1500
1000
500
Inte
nsity
(cps
)
NiTiMNiNd
NiTiA
(100) M
(minus101) M
(minus111) M
(020) M
(110) A
(111) M
(minus112) M
(132
)(112) M
(200) A
(211) A
(131) M
(212) M
(c)
Inte
nsity
2120579 (deg)44 45 46 47
(111)Mx = 20
x = 7
x = 3
x = 1
x = 0
(d)
Figure 1 XRD curves of Ni50Ti50minusxNdx alloys (a) XRD curves of Ni
50Ti50minusxNdx alloys (b) indexed diffraction peaks in Nd0 (c) indexed
diffraction peaks in Nd3 (d) comparison of (111)M diffraction peaks of Ni50Ti50minusxNdx alloys
phase overspreads steadily on the matrix with increasing Ndfraction
To identify the boundaries between the white phase andthe matrix TEM observation was conducted for Nd1 alloyand the TEM bright field images of a small nearly round-shaped particle with a diameter of 17120583m and a large nearlyround-shaped particle with a diameter of 36120583mare shown inFigure 3The boundaries between these two particles and thematrix look very bright and can be identified clearly at sucha very low magnification which means that the boundariesare incoherent Furthermore Xu et al proposed that thebinding force of RE elements and Ni is much bigger thanthat of Ni and Ti [11] So NiNd phase is formed first andthen NiTi phase crystallization occurs during the Ni-Ti-Ndalloys preparation Thus NiNd phase and NiTi matrix haveno orientation relationship [5]
To identify the phase structure EDS analysis was con-ducted in SEM The compositions of Ni-Ti-Nd alloys are
shown in Table 2 The Ti Ni ratio in the matrix of all Ni-Ti-Nd alloys is measured to be near 1 Thus the matrix can beconcluded to beNiTi phase with a small amount of Nd soluteTheTi Ni ratio in the black phase of Nd0 alloy ismeasured tobe near 2 1 By XRD analysis there is a NiTi
2phase in Nd0
Thus the black phase can be concluded to be NiTi2phase
According to the 773K isothermal section of the ternary alloyphase diagram of the Ni-Ti-Nd no intermetallic compoundscan be found in the Ti-Nd binary system However Ni-Ndbinary alloy phase diagram shows seven kinds of intermetalliccompounds defined as NdNi
5 Nd2Ni7 NdNi
3 NdNi
2 NdNi
Nd7Ni13 and Nd
3Ni [12] The EDS results show that the
Ni Nd ratio in the white phase is near 1 and can be regardedas the NiNd intermetallic compound with a small amount ofTi solute The amount and size of the NiNd phase increasewith increasing Nd fraction (Figure 2)
Furthermore Nd content has also been found in thematrix of Nd3 Nd7 and Nd20 The Nd atomic radius(0206 nm) is known to be larger than Ti atomic radius
4 Advances in Materials Science and Engineering
Ni50Ti50(a)
(a)
Ni50Ti49Nd1(b)
(b)
Ni50Ti47Nd3(c)
(c)
Ni50Ti43Nd7(d)
(d)
Ni50Ti30Nd20(e)
(e)
Figure 2 Back-scattering SEM images of Ni50Ti50minusxNdx alloys (a) Ni
50Ti50 (b) Ni
50Ti49Nd1 (c) Ni
50Ti47Nd3 (d) Ni
50Ti43Nd7 (e)
Ni50Ti30Nd20
(a) (b)
Figure 3 TEM bright field images of Ni50Ti49Nd1alloy (a) small particle (b) large particle
Advances in Materials Science and Engineering 5
Hea
t flow
x = 20
x = 7
x = 3
x = 1
x = 0
Cooling
Heating
Temperature (∘C)0 40 80 120
(a)
Tem
pera
ture
(∘C)
Nd concentration (at )0 5 10 15 20
80
60
40
20
0
minus20
minus40
minus60
Ni50Ti50minusxNdx
Nd0Ni507Ti493 [7]
Ni50Ti50 [14]Ni498Ti502 [15]
(b)
Figure 4 DSC curve and martensite transformation temperature of Ni50Ti50minus119909
Nd119909alloys (a) DSC curves (b)119872
119904curve
(0176 nm) by 17 and Ni atomic radius (0149 nm) by 38[13] The Nd atom occupies the position of Ni or Ti conse-quentially resulting in an expansion of the NiTi matrix lattice[7] which is consistent with the previous XRD analysis
33 Phase Transformation of Ni50Ti50minus119909
Nd119909
AlloysFigure 4(a) depicts theDSC curves of theNi
50Ti50minus119909
Nd119909(119909 =
0 1 3 7 20) alloys Each DSC curve of Nd0 Nd1 Nd3 Nd7and Nd20 shows only one peak during the heating andcooling process which indicates a one-step B2harrB191015840phase transformation Figure 4(b) shows the effect ofNd concentration on martensitic transformation starttemperature 119872
119904 For Nd0 alloy the 119872
119904is measured to
be 7744∘C It is well known that quenched Ni-Ti binaryalloys show one-step B2harrB191015840 transformation and thetransformation temperatures are strongly dependent on Niconcentration [5 7] 01 at increase in Ni concentrationcan lower the119872
119904of Ni-Ti binary alloys by more than 10∘C
For example Liu et al measured the119872119904to be about minus50∘C
for Ni507
Ti493
alloy after annealing at 900∘C for 60min [7]Tabish et al measured the 119872
119904to be minus2212∘C for Ni
50Ti50
alloy after annealing at 1000∘C for 120min [14] Wasilewskiet al measured the119872
119904to be 65∘C for Ni
498Ti502
alloy [15] Inthis work the composition of the matrix in Nd0 is measuredto be Ni
4936Ti5064
which is Ti-rich So a high 119872119904of Ti-
Ni binary alloy Nd0 is reasonable Again the martensitetransformations finish temperature 119872
119891in Nd0 alloy is
higher than room temperature of 20∘C Thus the martensitetransformations have finished at room temperature and theNd0 alloy should be in total martensite phase which is inagreement with the XRD results
Meanwhile as shown in Figure 4 the119872119904increases with
increasing Nd fraction from 1 at to 20 at And all 119872119891
in four DSC curves of Nd addition alloys are lower thanroom temperature Thus martensite transformation cannot
Table 2 Compositions of Ni-Ti-Nd alloys
Ti (at) Ni (at) Nd (at)
Nd0 Matrix 5064 4936 mdashBlack phase 6699 3301 mdash
Nd1 Matrix 5061 4939 0White phase 555 4967 4478
Nd3 Matrix 4924 5021 055White phase 297 4984 4719
Nd7 Matrix 4999 4895 106White phase 431 4772 4797
Nd20 Matrix 4927 4899 174White phase 168 4978 4854
finish fully at room temperature which indicates that boththe austenite phase and the martensite phase exist in the Ni-Ti-Nd alloy For Nd1 alloy the119872
119891is higher than the others
afterwhich themartensite transformation has nearly finishedThus a higher martensite fraction than austenite fraction ispresent Consequently the XRD curve of Nd1 shows that theintensities of themartensite diffraction peaks are significantlyhigher than those of austenite in Figure 1(a) With increasingNd fraction the 119872
119891 the martensite fraction in the alloy
and the relative XRD intensities of the martensite diffractionpeaks also decreased
4 Conclusions
In summary the effect of RE element Nd addition on themicrostructure and martensitic transformation behavior wasinvestigated by XRD SEM TEM and DSC The microstruc-ture of the Ni
50Ti50minus119909
Nd119909alloys consists of NiNd alloy with
a small amount of Ti solute and NiTi matrix with a small
6 Advances in Materials Science and Engineering
amount of Nd solute The lattice of NiTi matrix is expandedbyNd additionTheNi-Ti-Nd alloy has a one-stepmartensitictransformation Increasing the Nd fraction the martensitictransformation start temperature119872
119904increases gradually
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgments
This work was supported by the National Natural ScienceFoundation of China (Grant no 51261017) the Program forNew Century Excellent Talents in University (Grant noNCET-10-0909) and the Specialized Research Fund forthe Doctoral Program of Higher Education (Grant no20101514110002)
References
[1] K Otsuka and X Ren ldquoRecent developments in the research ofshape memory alloysrdquo Intermetallics vol 7 no 5 pp 511ndash5281999
[2] J Frenzel J Pfetzing K Neuking andG Eggeler ldquoOn the influ-ence of thermomechanical treatments on the microstructureand phase transformation behavior of Ni-Ti-Fe shape memoryalloysrdquo Materials Science and Engineering A vol 482ndash484 no1-2 pp 635ndash638 2008
[3] X L Meng W Cai Y D Fu Q F Li J X Zhang and L CZhao ldquoShape-memory behaviors in an aged Ni-rich TiNiHfhigh temperature shape-memory alloyrdquo Intermetallics vol 16no 5 pp 698ndash705 2008
[4] Y LiuM Kohl K Okutsu and SMiyazaki ldquoA TiNiPd thin filmmicrovalve for high temperature applicationsrdquoMaterials Scienceand Engineering A vol 378 no 1-2 pp 205ndash209 2004
[5] K Otsuka and X Ren ldquoPhysical metallurgy of Ti-Ni-basedshape memory alloysrdquo Progress in Materials Science vol 50 no5 pp 511ndash678 2005
[6] W Cai A L Liu J H Sui and L C Zhao ldquoEffects of ceriumaddition on martensitic transformation and microstructure ofTi493
Ni507
alloyrdquoMaterials Transactions vol 47 no 3 pp 716ndash719 2006
[7] A L LiuW Cai Z Y Gao and L C Zhao ldquoThemicrostructureand martensitic transformation of (Ti
493Ni507
)1minus119909
Gd119909shape
memory alloysrdquoMaterials Science and Engineering A vol 438ndash440 pp 634ndash638 2006
[8] A L Liu Z Y Gao L Gao W Cai and Y Wu ldquoEffect of Dyaddition on the microstructure and martensitic transformationof a Ni-rich TiNi shape memory alloyrdquo Journal of Alloys andCompounds vol 437 no 1-2 pp 339ndash343 2007
[9] J W Xu A L Liu B Y Qian and W Cai ldquoInvestigation onmicrostructure and phase transformation of La added TiNishape memory alloyrdquo Advanced Materials Research vol 557ndash559 pp 1041ndash1044 2012
[10] J GWang and F S Liu ldquoPhase transformation andmicrostruc-ture of Ti
50Ni48minus119909
Fe2Nd119909shapememory alloysrdquoChinese Journal
of Aeronautics vol 22 no 3 pp 334ndash338 2009[11] J-WXu A-L Liu andWCai ldquoCrystal structure and formation
mechanism of rare earth rich phases in Ti-Ni-Ce alloysrdquo Journal
of Functional Materials vol 39 no 4 pp 600ndash602 2008 (Chi-nese)
[12] J Q Liu Y H Zhuang and Y Q Hu ldquoThe 773K isothermalsection of the ternary phase diagram of the Nd-Ni-Tirdquo Journalof Alloys and Compounds vol 368 no 1-2 pp 180ndash181 2004
[13] E Clementi D L Raimondi and W P Reinhardt ldquoAtomicscreening constants from SCF functions II Atoms with 37 to86 electronsrdquoThe Journal of Chemical Physics vol 47 no 4 pp1300ndash1307 1967
[14] T A Tabish S Atiq M Ali A N Ch Z U Reham and T ZButt ldquoDevelopment and characterization of Ni
50Ti50
shapememory alloy used for biomedical applicationsrdquo InternationalJournal of Chemical Materials Science and Engineering vol 7no 12 pp 92ndash93 2013
[15] R JWasilewski S R Butler and J EHanlon ldquoOn themartensi-tic transformation in TiNirdquo Metallurgical Transactions vol 1no 1 pp 104ndash110 1967
Submit your manuscripts athttpwwwhindawicom
ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CorrosionInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Polymer ScienceInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CeramicsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CompositesJournal of
NanoparticlesJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
International Journal of
Biomaterials
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
NanoscienceJournal of
TextilesHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Journal of
NanotechnologyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
CrystallographyJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CoatingsJournal of
Advances in
Materials Science and EngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Smart Materials Research
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
MetallurgyJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
BioMed Research International
MaterialsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Nano
materials
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal ofNanomaterials
4 Advances in Materials Science and Engineering
Ni50Ti50(a)
(a)
Ni50Ti49Nd1(b)
(b)
Ni50Ti47Nd3(c)
(c)
Ni50Ti43Nd7(d)
(d)
Ni50Ti30Nd20(e)
(e)
Figure 2 Back-scattering SEM images of Ni50Ti50minusxNdx alloys (a) Ni
50Ti50 (b) Ni
50Ti49Nd1 (c) Ni
50Ti47Nd3 (d) Ni
50Ti43Nd7 (e)
Ni50Ti30Nd20
(a) (b)
Figure 3 TEM bright field images of Ni50Ti49Nd1alloy (a) small particle (b) large particle
Advances in Materials Science and Engineering 5
Hea
t flow
x = 20
x = 7
x = 3
x = 1
x = 0
Cooling
Heating
Temperature (∘C)0 40 80 120
(a)
Tem
pera
ture
(∘C)
Nd concentration (at )0 5 10 15 20
80
60
40
20
0
minus20
minus40
minus60
Ni50Ti50minusxNdx
Nd0Ni507Ti493 [7]
Ni50Ti50 [14]Ni498Ti502 [15]
(b)
Figure 4 DSC curve and martensite transformation temperature of Ni50Ti50minus119909
Nd119909alloys (a) DSC curves (b)119872
119904curve
(0176 nm) by 17 and Ni atomic radius (0149 nm) by 38[13] The Nd atom occupies the position of Ni or Ti conse-quentially resulting in an expansion of the NiTi matrix lattice[7] which is consistent with the previous XRD analysis
33 Phase Transformation of Ni50Ti50minus119909
Nd119909
AlloysFigure 4(a) depicts theDSC curves of theNi
50Ti50minus119909
Nd119909(119909 =
0 1 3 7 20) alloys Each DSC curve of Nd0 Nd1 Nd3 Nd7and Nd20 shows only one peak during the heating andcooling process which indicates a one-step B2harrB191015840phase transformation Figure 4(b) shows the effect ofNd concentration on martensitic transformation starttemperature 119872
119904 For Nd0 alloy the 119872
119904is measured to
be 7744∘C It is well known that quenched Ni-Ti binaryalloys show one-step B2harrB191015840 transformation and thetransformation temperatures are strongly dependent on Niconcentration [5 7] 01 at increase in Ni concentrationcan lower the119872
119904of Ni-Ti binary alloys by more than 10∘C
For example Liu et al measured the119872119904to be about minus50∘C
for Ni507
Ti493
alloy after annealing at 900∘C for 60min [7]Tabish et al measured the 119872
119904to be minus2212∘C for Ni
50Ti50
alloy after annealing at 1000∘C for 120min [14] Wasilewskiet al measured the119872
119904to be 65∘C for Ni
498Ti502
alloy [15] Inthis work the composition of the matrix in Nd0 is measuredto be Ni
4936Ti5064
which is Ti-rich So a high 119872119904of Ti-
Ni binary alloy Nd0 is reasonable Again the martensitetransformations finish temperature 119872
119891in Nd0 alloy is
higher than room temperature of 20∘C Thus the martensitetransformations have finished at room temperature and theNd0 alloy should be in total martensite phase which is inagreement with the XRD results
Meanwhile as shown in Figure 4 the119872119904increases with
increasing Nd fraction from 1 at to 20 at And all 119872119891
in four DSC curves of Nd addition alloys are lower thanroom temperature Thus martensite transformation cannot
Table 2 Compositions of Ni-Ti-Nd alloys
Ti (at) Ni (at) Nd (at)
Nd0 Matrix 5064 4936 mdashBlack phase 6699 3301 mdash
Nd1 Matrix 5061 4939 0White phase 555 4967 4478
Nd3 Matrix 4924 5021 055White phase 297 4984 4719
Nd7 Matrix 4999 4895 106White phase 431 4772 4797
Nd20 Matrix 4927 4899 174White phase 168 4978 4854
finish fully at room temperature which indicates that boththe austenite phase and the martensite phase exist in the Ni-Ti-Nd alloy For Nd1 alloy the119872
119891is higher than the others
afterwhich themartensite transformation has nearly finishedThus a higher martensite fraction than austenite fraction ispresent Consequently the XRD curve of Nd1 shows that theintensities of themartensite diffraction peaks are significantlyhigher than those of austenite in Figure 1(a) With increasingNd fraction the 119872
119891 the martensite fraction in the alloy
and the relative XRD intensities of the martensite diffractionpeaks also decreased
4 Conclusions
In summary the effect of RE element Nd addition on themicrostructure and martensitic transformation behavior wasinvestigated by XRD SEM TEM and DSC The microstruc-ture of the Ni
50Ti50minus119909
Nd119909alloys consists of NiNd alloy with
a small amount of Ti solute and NiTi matrix with a small
6 Advances in Materials Science and Engineering
amount of Nd solute The lattice of NiTi matrix is expandedbyNd additionTheNi-Ti-Nd alloy has a one-stepmartensitictransformation Increasing the Nd fraction the martensitictransformation start temperature119872
119904increases gradually
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgments
This work was supported by the National Natural ScienceFoundation of China (Grant no 51261017) the Program forNew Century Excellent Talents in University (Grant noNCET-10-0909) and the Specialized Research Fund forthe Doctoral Program of Higher Education (Grant no20101514110002)
References
[1] K Otsuka and X Ren ldquoRecent developments in the research ofshape memory alloysrdquo Intermetallics vol 7 no 5 pp 511ndash5281999
[2] J Frenzel J Pfetzing K Neuking andG Eggeler ldquoOn the influ-ence of thermomechanical treatments on the microstructureand phase transformation behavior of Ni-Ti-Fe shape memoryalloysrdquo Materials Science and Engineering A vol 482ndash484 no1-2 pp 635ndash638 2008
[3] X L Meng W Cai Y D Fu Q F Li J X Zhang and L CZhao ldquoShape-memory behaviors in an aged Ni-rich TiNiHfhigh temperature shape-memory alloyrdquo Intermetallics vol 16no 5 pp 698ndash705 2008
[4] Y LiuM Kohl K Okutsu and SMiyazaki ldquoA TiNiPd thin filmmicrovalve for high temperature applicationsrdquoMaterials Scienceand Engineering A vol 378 no 1-2 pp 205ndash209 2004
[5] K Otsuka and X Ren ldquoPhysical metallurgy of Ti-Ni-basedshape memory alloysrdquo Progress in Materials Science vol 50 no5 pp 511ndash678 2005
[6] W Cai A L Liu J H Sui and L C Zhao ldquoEffects of ceriumaddition on martensitic transformation and microstructure ofTi493
Ni507
alloyrdquoMaterials Transactions vol 47 no 3 pp 716ndash719 2006
[7] A L LiuW Cai Z Y Gao and L C Zhao ldquoThemicrostructureand martensitic transformation of (Ti
493Ni507
)1minus119909
Gd119909shape
memory alloysrdquoMaterials Science and Engineering A vol 438ndash440 pp 634ndash638 2006
[8] A L Liu Z Y Gao L Gao W Cai and Y Wu ldquoEffect of Dyaddition on the microstructure and martensitic transformationof a Ni-rich TiNi shape memory alloyrdquo Journal of Alloys andCompounds vol 437 no 1-2 pp 339ndash343 2007
[9] J W Xu A L Liu B Y Qian and W Cai ldquoInvestigation onmicrostructure and phase transformation of La added TiNishape memory alloyrdquo Advanced Materials Research vol 557ndash559 pp 1041ndash1044 2012
[10] J GWang and F S Liu ldquoPhase transformation andmicrostruc-ture of Ti
50Ni48minus119909
Fe2Nd119909shapememory alloysrdquoChinese Journal
of Aeronautics vol 22 no 3 pp 334ndash338 2009[11] J-WXu A-L Liu andWCai ldquoCrystal structure and formation
mechanism of rare earth rich phases in Ti-Ni-Ce alloysrdquo Journal
of Functional Materials vol 39 no 4 pp 600ndash602 2008 (Chi-nese)
[12] J Q Liu Y H Zhuang and Y Q Hu ldquoThe 773K isothermalsection of the ternary phase diagram of the Nd-Ni-Tirdquo Journalof Alloys and Compounds vol 368 no 1-2 pp 180ndash181 2004
[13] E Clementi D L Raimondi and W P Reinhardt ldquoAtomicscreening constants from SCF functions II Atoms with 37 to86 electronsrdquoThe Journal of Chemical Physics vol 47 no 4 pp1300ndash1307 1967
[14] T A Tabish S Atiq M Ali A N Ch Z U Reham and T ZButt ldquoDevelopment and characterization of Ni
50Ti50
shapememory alloy used for biomedical applicationsrdquo InternationalJournal of Chemical Materials Science and Engineering vol 7no 12 pp 92ndash93 2013
[15] R JWasilewski S R Butler and J EHanlon ldquoOn themartensi-tic transformation in TiNirdquo Metallurgical Transactions vol 1no 1 pp 104ndash110 1967
Submit your manuscripts athttpwwwhindawicom
ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CorrosionInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Polymer ScienceInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CeramicsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CompositesJournal of
NanoparticlesJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
International Journal of
Biomaterials
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
NanoscienceJournal of
TextilesHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Journal of
NanotechnologyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
CrystallographyJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CoatingsJournal of
Advances in
Materials Science and EngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Smart Materials Research
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
MetallurgyJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
BioMed Research International
MaterialsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Nano
materials
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal ofNanomaterials
Advances in Materials Science and Engineering 5
Hea
t flow
x = 20
x = 7
x = 3
x = 1
x = 0
Cooling
Heating
Temperature (∘C)0 40 80 120
(a)
Tem
pera
ture
(∘C)
Nd concentration (at )0 5 10 15 20
80
60
40
20
0
minus20
minus40
minus60
Ni50Ti50minusxNdx
Nd0Ni507Ti493 [7]
Ni50Ti50 [14]Ni498Ti502 [15]
(b)
Figure 4 DSC curve and martensite transformation temperature of Ni50Ti50minus119909
Nd119909alloys (a) DSC curves (b)119872
119904curve
(0176 nm) by 17 and Ni atomic radius (0149 nm) by 38[13] The Nd atom occupies the position of Ni or Ti conse-quentially resulting in an expansion of the NiTi matrix lattice[7] which is consistent with the previous XRD analysis
33 Phase Transformation of Ni50Ti50minus119909
Nd119909
AlloysFigure 4(a) depicts theDSC curves of theNi
50Ti50minus119909
Nd119909(119909 =
0 1 3 7 20) alloys Each DSC curve of Nd0 Nd1 Nd3 Nd7and Nd20 shows only one peak during the heating andcooling process which indicates a one-step B2harrB191015840phase transformation Figure 4(b) shows the effect ofNd concentration on martensitic transformation starttemperature 119872
119904 For Nd0 alloy the 119872
119904is measured to
be 7744∘C It is well known that quenched Ni-Ti binaryalloys show one-step B2harrB191015840 transformation and thetransformation temperatures are strongly dependent on Niconcentration [5 7] 01 at increase in Ni concentrationcan lower the119872
119904of Ni-Ti binary alloys by more than 10∘C
For example Liu et al measured the119872119904to be about minus50∘C
for Ni507
Ti493
alloy after annealing at 900∘C for 60min [7]Tabish et al measured the 119872
119904to be minus2212∘C for Ni
50Ti50
alloy after annealing at 1000∘C for 120min [14] Wasilewskiet al measured the119872
119904to be 65∘C for Ni
498Ti502
alloy [15] Inthis work the composition of the matrix in Nd0 is measuredto be Ni
4936Ti5064
which is Ti-rich So a high 119872119904of Ti-
Ni binary alloy Nd0 is reasonable Again the martensitetransformations finish temperature 119872
119891in Nd0 alloy is
higher than room temperature of 20∘C Thus the martensitetransformations have finished at room temperature and theNd0 alloy should be in total martensite phase which is inagreement with the XRD results
Meanwhile as shown in Figure 4 the119872119904increases with
increasing Nd fraction from 1 at to 20 at And all 119872119891
in four DSC curves of Nd addition alloys are lower thanroom temperature Thus martensite transformation cannot
Table 2 Compositions of Ni-Ti-Nd alloys
Ti (at) Ni (at) Nd (at)
Nd0 Matrix 5064 4936 mdashBlack phase 6699 3301 mdash
Nd1 Matrix 5061 4939 0White phase 555 4967 4478
Nd3 Matrix 4924 5021 055White phase 297 4984 4719
Nd7 Matrix 4999 4895 106White phase 431 4772 4797
Nd20 Matrix 4927 4899 174White phase 168 4978 4854
finish fully at room temperature which indicates that boththe austenite phase and the martensite phase exist in the Ni-Ti-Nd alloy For Nd1 alloy the119872
119891is higher than the others
afterwhich themartensite transformation has nearly finishedThus a higher martensite fraction than austenite fraction ispresent Consequently the XRD curve of Nd1 shows that theintensities of themartensite diffraction peaks are significantlyhigher than those of austenite in Figure 1(a) With increasingNd fraction the 119872
119891 the martensite fraction in the alloy
and the relative XRD intensities of the martensite diffractionpeaks also decreased
4 Conclusions
In summary the effect of RE element Nd addition on themicrostructure and martensitic transformation behavior wasinvestigated by XRD SEM TEM and DSC The microstruc-ture of the Ni
50Ti50minus119909
Nd119909alloys consists of NiNd alloy with
a small amount of Ti solute and NiTi matrix with a small
6 Advances in Materials Science and Engineering
amount of Nd solute The lattice of NiTi matrix is expandedbyNd additionTheNi-Ti-Nd alloy has a one-stepmartensitictransformation Increasing the Nd fraction the martensitictransformation start temperature119872
119904increases gradually
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgments
This work was supported by the National Natural ScienceFoundation of China (Grant no 51261017) the Program forNew Century Excellent Talents in University (Grant noNCET-10-0909) and the Specialized Research Fund forthe Doctoral Program of Higher Education (Grant no20101514110002)
References
[1] K Otsuka and X Ren ldquoRecent developments in the research ofshape memory alloysrdquo Intermetallics vol 7 no 5 pp 511ndash5281999
[2] J Frenzel J Pfetzing K Neuking andG Eggeler ldquoOn the influ-ence of thermomechanical treatments on the microstructureand phase transformation behavior of Ni-Ti-Fe shape memoryalloysrdquo Materials Science and Engineering A vol 482ndash484 no1-2 pp 635ndash638 2008
[3] X L Meng W Cai Y D Fu Q F Li J X Zhang and L CZhao ldquoShape-memory behaviors in an aged Ni-rich TiNiHfhigh temperature shape-memory alloyrdquo Intermetallics vol 16no 5 pp 698ndash705 2008
[4] Y LiuM Kohl K Okutsu and SMiyazaki ldquoA TiNiPd thin filmmicrovalve for high temperature applicationsrdquoMaterials Scienceand Engineering A vol 378 no 1-2 pp 205ndash209 2004
[5] K Otsuka and X Ren ldquoPhysical metallurgy of Ti-Ni-basedshape memory alloysrdquo Progress in Materials Science vol 50 no5 pp 511ndash678 2005
[6] W Cai A L Liu J H Sui and L C Zhao ldquoEffects of ceriumaddition on martensitic transformation and microstructure ofTi493
Ni507
alloyrdquoMaterials Transactions vol 47 no 3 pp 716ndash719 2006
[7] A L LiuW Cai Z Y Gao and L C Zhao ldquoThemicrostructureand martensitic transformation of (Ti
493Ni507
)1minus119909
Gd119909shape
memory alloysrdquoMaterials Science and Engineering A vol 438ndash440 pp 634ndash638 2006
[8] A L Liu Z Y Gao L Gao W Cai and Y Wu ldquoEffect of Dyaddition on the microstructure and martensitic transformationof a Ni-rich TiNi shape memory alloyrdquo Journal of Alloys andCompounds vol 437 no 1-2 pp 339ndash343 2007
[9] J W Xu A L Liu B Y Qian and W Cai ldquoInvestigation onmicrostructure and phase transformation of La added TiNishape memory alloyrdquo Advanced Materials Research vol 557ndash559 pp 1041ndash1044 2012
[10] J GWang and F S Liu ldquoPhase transformation andmicrostruc-ture of Ti
50Ni48minus119909
Fe2Nd119909shapememory alloysrdquoChinese Journal
of Aeronautics vol 22 no 3 pp 334ndash338 2009[11] J-WXu A-L Liu andWCai ldquoCrystal structure and formation
mechanism of rare earth rich phases in Ti-Ni-Ce alloysrdquo Journal
of Functional Materials vol 39 no 4 pp 600ndash602 2008 (Chi-nese)
[12] J Q Liu Y H Zhuang and Y Q Hu ldquoThe 773K isothermalsection of the ternary phase diagram of the Nd-Ni-Tirdquo Journalof Alloys and Compounds vol 368 no 1-2 pp 180ndash181 2004
[13] E Clementi D L Raimondi and W P Reinhardt ldquoAtomicscreening constants from SCF functions II Atoms with 37 to86 electronsrdquoThe Journal of Chemical Physics vol 47 no 4 pp1300ndash1307 1967
[14] T A Tabish S Atiq M Ali A N Ch Z U Reham and T ZButt ldquoDevelopment and characterization of Ni
50Ti50
shapememory alloy used for biomedical applicationsrdquo InternationalJournal of Chemical Materials Science and Engineering vol 7no 12 pp 92ndash93 2013
[15] R JWasilewski S R Butler and J EHanlon ldquoOn themartensi-tic transformation in TiNirdquo Metallurgical Transactions vol 1no 1 pp 104ndash110 1967
Submit your manuscripts athttpwwwhindawicom
ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CorrosionInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Polymer ScienceInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CeramicsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CompositesJournal of
NanoparticlesJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
International Journal of
Biomaterials
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
NanoscienceJournal of
TextilesHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Journal of
NanotechnologyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
CrystallographyJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CoatingsJournal of
Advances in
Materials Science and EngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Smart Materials Research
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
MetallurgyJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
BioMed Research International
MaterialsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Nano
materials
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal ofNanomaterials
6 Advances in Materials Science and Engineering
amount of Nd solute The lattice of NiTi matrix is expandedbyNd additionTheNi-Ti-Nd alloy has a one-stepmartensitictransformation Increasing the Nd fraction the martensitictransformation start temperature119872
119904increases gradually
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgments
This work was supported by the National Natural ScienceFoundation of China (Grant no 51261017) the Program forNew Century Excellent Talents in University (Grant noNCET-10-0909) and the Specialized Research Fund forthe Doctoral Program of Higher Education (Grant no20101514110002)
References
[1] K Otsuka and X Ren ldquoRecent developments in the research ofshape memory alloysrdquo Intermetallics vol 7 no 5 pp 511ndash5281999
[2] J Frenzel J Pfetzing K Neuking andG Eggeler ldquoOn the influ-ence of thermomechanical treatments on the microstructureand phase transformation behavior of Ni-Ti-Fe shape memoryalloysrdquo Materials Science and Engineering A vol 482ndash484 no1-2 pp 635ndash638 2008
[3] X L Meng W Cai Y D Fu Q F Li J X Zhang and L CZhao ldquoShape-memory behaviors in an aged Ni-rich TiNiHfhigh temperature shape-memory alloyrdquo Intermetallics vol 16no 5 pp 698ndash705 2008
[4] Y LiuM Kohl K Okutsu and SMiyazaki ldquoA TiNiPd thin filmmicrovalve for high temperature applicationsrdquoMaterials Scienceand Engineering A vol 378 no 1-2 pp 205ndash209 2004
[5] K Otsuka and X Ren ldquoPhysical metallurgy of Ti-Ni-basedshape memory alloysrdquo Progress in Materials Science vol 50 no5 pp 511ndash678 2005
[6] W Cai A L Liu J H Sui and L C Zhao ldquoEffects of ceriumaddition on martensitic transformation and microstructure ofTi493
Ni507
alloyrdquoMaterials Transactions vol 47 no 3 pp 716ndash719 2006
[7] A L LiuW Cai Z Y Gao and L C Zhao ldquoThemicrostructureand martensitic transformation of (Ti
493Ni507
)1minus119909
Gd119909shape
memory alloysrdquoMaterials Science and Engineering A vol 438ndash440 pp 634ndash638 2006
[8] A L Liu Z Y Gao L Gao W Cai and Y Wu ldquoEffect of Dyaddition on the microstructure and martensitic transformationof a Ni-rich TiNi shape memory alloyrdquo Journal of Alloys andCompounds vol 437 no 1-2 pp 339ndash343 2007
[9] J W Xu A L Liu B Y Qian and W Cai ldquoInvestigation onmicrostructure and phase transformation of La added TiNishape memory alloyrdquo Advanced Materials Research vol 557ndash559 pp 1041ndash1044 2012
[10] J GWang and F S Liu ldquoPhase transformation andmicrostruc-ture of Ti
50Ni48minus119909
Fe2Nd119909shapememory alloysrdquoChinese Journal
of Aeronautics vol 22 no 3 pp 334ndash338 2009[11] J-WXu A-L Liu andWCai ldquoCrystal structure and formation
mechanism of rare earth rich phases in Ti-Ni-Ce alloysrdquo Journal
of Functional Materials vol 39 no 4 pp 600ndash602 2008 (Chi-nese)
[12] J Q Liu Y H Zhuang and Y Q Hu ldquoThe 773K isothermalsection of the ternary phase diagram of the Nd-Ni-Tirdquo Journalof Alloys and Compounds vol 368 no 1-2 pp 180ndash181 2004
[13] E Clementi D L Raimondi and W P Reinhardt ldquoAtomicscreening constants from SCF functions II Atoms with 37 to86 electronsrdquoThe Journal of Chemical Physics vol 47 no 4 pp1300ndash1307 1967
[14] T A Tabish S Atiq M Ali A N Ch Z U Reham and T ZButt ldquoDevelopment and characterization of Ni
50Ti50
shapememory alloy used for biomedical applicationsrdquo InternationalJournal of Chemical Materials Science and Engineering vol 7no 12 pp 92ndash93 2013
[15] R JWasilewski S R Butler and J EHanlon ldquoOn themartensi-tic transformation in TiNirdquo Metallurgical Transactions vol 1no 1 pp 104ndash110 1967
Submit your manuscripts athttpwwwhindawicom
ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CorrosionInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Polymer ScienceInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CeramicsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CompositesJournal of
NanoparticlesJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
International Journal of
Biomaterials
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
NanoscienceJournal of
TextilesHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Journal of
NanotechnologyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
CrystallographyJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CoatingsJournal of
Advances in
Materials Science and EngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Smart Materials Research
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
MetallurgyJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
BioMed Research International
MaterialsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Nano
materials
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal ofNanomaterials
Submit your manuscripts athttpwwwhindawicom
ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CorrosionInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Polymer ScienceInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CeramicsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CompositesJournal of
NanoparticlesJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
International Journal of
Biomaterials
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
NanoscienceJournal of
TextilesHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Journal of
NanotechnologyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
CrystallographyJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CoatingsJournal of
Advances in
Materials Science and EngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Smart Materials Research
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
MetallurgyJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
BioMed Research International
MaterialsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Nano
materials
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal ofNanomaterials