马氏体相变微结构演化过程的模拟与分析

实验中观察到形状记忆合金在应力诱发马氏体相变过程中,出现多界面的微结构,马氏体相会逐渐长大变粗,同时会出现由马氏体形核造成的应力突然降低.用多阱的弹性能函数来刻画此相变与微结构演化过程,发现相变时会出现多界面的微结构且伴随着马氏体相的形核至奥氏体相的消失过程,出现了界面数先增后减的变化,同时应力会出现跳跃而不连续.相对应的动力学模型的有限差分的计算结果同样显示形核时出现了多界面的微结构并伴随着应力的大幅振荡,随着载荷的增加界面位置随之移动,使得马氏体相区域逐渐长大.理论分析与数值模拟的结果较好地刻画了实验中观察到的马氏体相变过程中的形核,产生多界面,再到马氏体逐渐长大这一微结构的演化过程.

SIMULATION AND ANALYSIS OF THE MICROSTRUCTURE EVOLUTION DURING MARTENSITIC PHASE TRANSITION

It has been observed in experiments that multi-interface microstructures can form and the martensitic phase regions grow wider during the stress-induced martensitic phase transition of shape memory alloys.As the martensitic phase nucleates,stress drop can occur.We used a multi-well elastic energy to simulate the process of phase transition and microstructure evolution.With the nucleation of the martensitic phase and the disappearance of the austenite phase,the number of the interfaces will undergo an increase to decrease process.Meanwhile,the stress drops and becomes discontinuous.The computation results of the relevant dynamic model shows the multi-interface microstructures in the process of nucleation during which the stress oscillates dramatically.The interface position moves with the progress of the loading.This makes martensitic phase grow up.The results of theoretical analysis and numerical simulation describe the whole process of the microstructure evolution which has been observed in the experiment well.