热及应力诱发Ti_(50)Ni_(49.5)Fe_(0.5)的马氏体相变织构研究

Texture Evolvement of Thermal and Stress Induced Martensite Phase Transformation in Ti_(50)Ni_(49.5)Fe_(0.5)Alloy

采用极图和取向分布函数方法研究了Ti50Ni49.5Fe0.5形状记忆合金的马氏体相变织构和变体选择规律,比较了热诱发和应力诱发之差异。结果表明,奥氏体主要含有(111)纤维织构和(111)[-1-12]板织构。热诱发的马氏体主要含有(102),(10-2)和(120)系列织构,按照马氏体相变的Bain畸变晶体学唯象理论,分析了所有马氏体孪生变体的织构演变规律,表明热诱发马氏体中12种变体均存在;但应力诱发马氏体相变,变体选择具有择优性,择优规律遵循Schmid定律,即主要是S因子最大和次大的1,2',3',4'和2,4变体,但也伴随着微弱的低S因子变体5,6,6',可能是多晶的催化协同作用,马氏体再取向等原因引起的。

The texture of austenite and martensite in Tis0 Ni49.s Feo.5 alloy was studied using pole figures and orientation distribution function （ODF）, and the differences in variants selection and texture development between the thermal induced and stress inducedmartensite phase transformation were discussed. The results showed that ： the main texture components were （ 111 ） fiber and （ 111 ） [-1-12] in austenite. There were （102）, （10-2） and （120） texture components in the thermal induced martensite. The texture trans-formation of all the martensite twining variants was analyzed according to the Bain crystalline phenomenological theory. The results implied that all of the 12 variants were present in the thermal induced martensite. However, the main variants, 1,2＇, 3＇, 4＇ with the lar-gest S factor and 2, 4 with the second largest S factor, growing in the stress induced martensite were preferential followed by the Schmid law. Besides that, few of variants with low or even negative S factors still existed, the main reasons were the cooperative-catalytic effectamong neighboring grains in polycrystalline and the martensite reorientation during the plastic deformation.