強磁場耦合下的馬氏體相變

1、451Vol.45No.1200913742ACTA METALLURGICA SINICA Jan.2009pp.3742 LandauTiNi/(,116024LandauTiNi/.TiNi(Fermi,Landau.,(M sT 0,.,.5TTiNi,TEM(,.,Landau,TiNiTG139.6A04121961(200901003706MARTENSITE TRANSFORMATION IN TiNi ALLOY UN-DER COUPLING TEMPERATURE AND HIGH MAGNETIC FIELD USING LANDAU THEORY MODELZHENG

2、 Bin,ZHOU Wei,WANG Yinong,QI MinSchool of Materials Science and Engineering,Dalian University of Technology,Dalian 116024Manuscript received 20080310,in revised form 20080903ABSTRACT The martensitic transformation behavior under coupling temperature and high mag-netic eld in TiNi paramagnetic shape

3、memory alloy was studied by using the modied Landau model.In order to introduce the eect of high magnetic eld,the Fermi surface total density of state (DOSof TiNi alloy under dierent phasetransformed shear strain (order parameterwas calculated by using the rstprinciples calculations,then the relatio

4、nship between magnetic susceptibility and shear strain was carried out.The calculation results from the modied Landau model involving the eect of mag-netic free energy indicated that the martensitic transformation temperatures (M s and T 0suddenly increase.It can be mainly contributed to the parabol

5、a increasing of martensitic transformation driving force under coupling temperature and high magnetic eld.Also,it is found that the oriented growth of martensitic variants occurs under coupling temperature and high magnetic eld due to the increased dierence of free energy between variants,which is c

6、onsistent with the TEM observation that some vertical twovariants are present in TiNi alloy under 5T magnetic eld.KEY WORDS martensite transformation,Landau theory,high magnetic eld,magnetic suscep-tibility,oriented growth,TiNi alloy,*5053102050471067:20080310,:20080903:,1981,.(TiNi1,2.(,/.,3845(FSM

7、A.(>5T,.RBaCuO,3;Y1Ba2Cu3O7,4;,5.,.,68NiMnGa9,10.(TiNi/11.NiMnGa,;,.Landau,Falk12.Falk,/;,.11.1Falk12,(TiNi,NiAl, CuZn,CuAlNi,AgCd AuCd110 110 .,Landau,:F(E,T=0E60E4+(0T0E2(1 ,F;E;T;0,0,00.(1,Zeeman67.,:F=m T·H(1/2·h(T·H2+0(/H·H·B0(2 ,m T;H;h,(FeNi ;0;(/H·H;B0.6,7,(2

8、,:.,8:F=(1/2··H2(3 ,.(3(1,T E.CurieWeiss,T;T,.E.1.2,.,;,Fermi.N =(1/2·N(E0F·B·B(4 ,N(E0FFermi,B Bohr, B.2B,M=N(E0F·0·2B·H(5 ,0.,=N(E0F·0·2B(6(6,Fermi,Fermi. CASTEP(Cambridge serial total energy package B2TiNi,B2Ni,0.3014 nm13,110 110 .(ultrasoft pseu

9、dopotential,(general gradient approximation,GGA,PerdewBurkeErnzerhof(PBE14.310eV,k8×6×6,1%.1.,Fermi,6.6542, FermiN(E0F=A·E6+B·E5C·E4(7 ,A,B C,.(7(6,(1 (3,:39 F(E,N A H=(10,(re=3/202TiNiFig.2Reduced free energy(f recurves of TiNi alloys under dierent reduced temperatures(t re

10、,shear strains(e reand magneticelds(h re 40 45 .,. Fig.3,M s.(11,M+, and1:LandauTiNi/41M s,e re,(,(selfaccommodation15.(h re =0.25,1.00,1.25,(h re =1.25.,M+,M+M+;M,M(T M ,(h re =1.50,T M ,M+.,/,.3,TEMTiNi5T.50mm5mm1mmTiNi .8501h,.DSC,:M s =45M f =32,.(JMTS10T 100.1805T ,.,TecnaiG 220TEM.TiNiB2(CsCl,

11、a =0.3014nm.TiNiB19(B19,P 21/m ,a =0.2898nm,b =0.4108nm,c =0.4646nm;=97.7816.TiNi15,17,3100B2,.5aTiNi TEM ,;(SAD(5b, 011 II;5c TiNi/TEM,TiNi/, 5Ti50.6%NiFig.5TEM martensitic morphologies and SAD patterns in Ti50.6%Ni (atomic fractionalloy without (a,bandwith 5T magnetic eld (c,d 42 Á Ò

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13、0;ઠ45 Æ Ø¹ TiNi ß Ù Ï ÍÛ, ª Á Á Fermi Ï ÍÛ ¯ , Á Ý Ê , ¤Á½ºÕÓ Landau ²Á . ع : Á½ Û hre >1.00 , ¨Û (1 Ms Õ &#

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