Ni53.2Mn22.6Ga24.2单晶的两步热弹性马氏体相变及其应力应变特性

Two-step thermoelastic martensitic transformation and stress-strain characteristic of Ni_(53.2)Mn_(22.6)Ga_(24.2) single crystal

对具有两步完全热弹性的Ni53.2Mn22.6Ga24.2单晶的物性采用多种测量手段进行了表征,特别研究了不同温度下的应力-应变特性.研究表明,热诱发的中间马氏体相变应变远大于马氏体相变应变.在较低的形变温度下,沿单晶母相[001]方向的压应力诱发的是两步马氏体相变,材料表现出赝弹性;在较高的形变温度下,只能观察到一步马氏体相变,材料展现出完全超弹性特性.此外,利用热力学理论分别计算了诱发马氏体相变和中间马氏体相变的临界应力与形变温度的关系,与实验测量得到的结果相符.

Physical properties of the two-step complete thermoelastic Ni53.2Mn22.6Ga24.2 single crystal are investigated by various measuring methods,especially,the stress-strain characteristic at different temperatures is studied. The results show that at low deformation temperatures the pressing stress along the [001] direction of the parent phase would induce a two-step martensitic transformation,and the alloy exhibits pseudoelastic characteristics. But at relatively high temperatures,the alloy exhibits complete superelastic characteristics,and only one-step martensitic transformation is observed. Furthermore,the dependence of critical stress on the deformation temperature for the martensitic transformation and intermartensitic transformation is calculated by the thermodynamic theory,and the result is consistent with that of two-step martensitic transformation obtained by experiment.