Pd掺杂对NiTi合金马氏体相变和热滞影响的第一性原理研究  

Effect of Pd in Ni Ti on the martensitic transformation temperatures and hysteresis: a first-principles study

作　　者：马蕾[1] 王旭[1] 尚家香[1] 

机构地区：[1]北京航空航天大学材料科学与工程学院,北京100191

出　　处：《物理学报》2014年第23期128-133,共6页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:51371017)资助的课题~~

摘　　要：一定浓度的Pd掺杂能够有效地提高Ni Ti合金的相变温度,并且降低热滞.为了解其作用机理,采用第一性原理计算方法,对不同Pd掺杂浓度下Ni Ti合金(Ni24-n Pd n Ti24,n=2,3,4,5,6,9,12;掺杂浓度分别为4.2 at.%,6.3 at.%,8.4 at.%,10.4 at.%,12.5 at.%,18.8 at.%,25 at.%)的相稳定性和结构特性进行计算讨论.马氏体相变温度可以通过奥氏体与马氏体两相能量差值进行分析,且能量差越大相变温度越高;相变过程中两相晶格常数之比越接近于1则热滞越接近于0.计算结果表明:当掺杂浓度小于10.4 at.%时,B19′是最稳定的马氏体相,体心四方(BCT)结构与B19′相的能量差随掺杂浓度的增加略有下降;当掺杂浓度大于等于10.4 at.%时,B19相是最稳定的马氏体相,BCT与B19的能量差随着掺杂浓度增加显著升高.这意味着在掺杂浓度大于等于10.4 at.%时相变温度随掺杂浓度的增加而显著增加.用几何模型分析了马氏体相变的热滞,结果表明掺杂浓度为10.4 at.%时B2到B19相的相变过程热滞最小,与实验结果一致.In this paper phase stability and functional properties of Pd-doped Ni Ti with different Pd concentrations（Ni24-n Pd n Ti24, n = 2, 3, 4, 5, 6, 9, 12; C Pd= 4.2 at.%, 6.3 at.%, 8.4 at.%, 10.4 at.%, 12.5 at.%, 18.8 at.% and25 at.%） are calculated by first-principles method. Results show that B19′is the most stable when C Pd is less than 10.4at.%, whereas B19 is the most stable for C Pd is equal to or larger than 10.4 at.%. The formation energy decreases with increasing Pd concentration. With increasing C Pd, the energy difference between austenite and martensite decreases slightly and increases for C Pd〈 10.4 at.% and 10.4 at.%, respectively. This indicates that the phase transition temperature decreases slightly and increases evidently for C Pd 〈10.4 at.% and 10.4 at.%, respectively, which is consistent with the experimental results. A geometric model is used to evaluate the hysteresis： when the ratio of the lattice constants of the two phases is close to 1, the hysteresis tends to zero. For Pd-doped Ni Ti, the lowest hysteresis is achieved at C Pd= 10.4 at.%, which agrees well with the experimental results.

关 键 词：第一性原理 Pd掺杂 马氏体相变 NITI 

分 类 号：O469[理学—凝聚态物理]