塑性变形提高形状记忆合金相变滞后机制的探讨

Origin of transformation hysteresis expansion by deformation of shape memory alloys

形状记忆合金经适当温度下的塑性变形可以有效地提高马氏体的稳定性 ,从而使相变滞后得以大幅度提高。本文根据马氏体相变热力学和动力学 ,并结合相关的实验结果 ,研究了弹性应变能弛豫和相变滞后的关系。结果表明 ,塑性变形产生的位错以及变形的第二相颗粒对逆马氏体相变温度的提高具有一定作用 ,但塑性变形导致应变能释放才是形变提高形状记忆合金相变滞后的主导因素。

Recent experimental investigations have demonstrated that the pre deformation of shape memory alloys results in martensite stabilization opposing reverse transformation, hence leading to the expansion of transformation hysteresis. Here a kinetic study has been made in order to determine the relationship between the relaxation of elastic energy and the hysteresis expansion by pre deformation of shape memory alloys. It is indicated that the relaxation of elastic energy stored during the forward martensitic transformation is responsible for the expansion of transformation hysteresis, which is in good agreement with experimental results associated with the hysteresis enlargement by deformation of NiTi, NiTi based and CuAlNi shape memory alloys.