NiTi合金B2-B19′马氏体相变晶体学的拓扑模拟研究  

Topological Modelling of the B2-B19' Martensite Transformation Crystallography in NiTi Alloy

作　　者：韦昭召 马骁[2] 张新平[2] Zhaozhao WEI;Xiao MA;Xinping ZHANG(School of Mechanical and Electrical Engineering,Wuyi University,Jiangmen 529020,China;School of Materials Science and Engineering,South China University of Technology,Guangzhou 510640,China)

机构地区：[1]五邑大学机电工程学院,江门529020 [2]华南理工大学材料科学与工程学院,广州510640

出　　处：《金属学报》2018年第10期1461-1470,共10页Acta Metallurgica Sinica

基　　金：国家自然科学基金项目No.51571092;广东省自然科学基金项目No.2017A030310657;广东省"创新强校工程"青年创新人才类项目No.2016KQNCX170;五邑大学博士启动基金项目No.2015BS16~~

摘　　要：运用拓扑模型研究了等原子比NiTi合金B2-B19'马氏体相变晶体学,根据最优扭转角(wo)准则计算得到wo=-0.969°,并获得了马氏体惯习面指数及母相-马氏体相界面位错结构特征,计算结果与实验测量值非常接近。NiTi合金马氏体相变所产生的相变应变包含一个平行于惯习面的剪切应变和一个垂直于惯习面的轴向应变,轴向应变量表示B2-B19'相变所引起的宏观体积变化为εHP33=6.6879×10-3,表明NiTi合金的负热膨胀现象来源于合金中马氏体相变所产生的相变应变。Some NiTi alloys, generally known as shape memory alloys or smart materials, exhibit larger negative thermal expansion （NTE） strain than that of traditional nonmetallic NTE materials. Furthermore, high strength and better ductility of NiTi alloy make it more advantageous compared to nonmetallic materials. The NTE response of NiTi alloy may be attributed to the transformation strain that originates from the volume change accompanying the B2-B19＇ martensitic transformation in the alloy. Therefore, it is of great importance and interests to study the martensitic transformation crystallography in NiTi alloy. In this work, the martensitic transformation crystallography in an equiatomic NiTi alloy was investigated by using the topological model, as well as the optimum twist criterion developed lately. The optimum twist angle, ωo, in NiTi alloy was determined to be -0.969°, and the so-obtained transformation crystallography results, including the habit plane index and parent-martensite orientation relationship, agree well with the corresponding experimental data and theoretical calculations in the literature. Furthermore, the martensitic transformation strain of NiTi alloy was calculated based on the analysis of interfacial dislocation movement, and the total transformation strain can be resolved into an in-habit-plane shear strain and an axial strain perpendicular to the habit plane. In particular, the value of the axial strain that represents the volume change due to the B19＇ to B2 transformation was found to be negative, indicating that the NiTi alloy shrinks during the reverse martensitic phase transformation when heated, which might shed some light on the relationship between the NTE mechanism and martensitic transformation in NiTi alloy. The measured NTE strain is much smaller than the theoretical calculated phase transformation strain in NiTi alloy, due to the self-accommodation effect of martensite variants and the compensation of transformation strains in polycrystalline materials.

关 键 词：拓扑模型 NITI合金 马氏体相变晶体学 相变应变 负热膨胀 

分 类 号：TG131[一般工业技术—材料科学与工程] TG139[金属学及工艺—合金]