承受各种循环加载的TiNi形状记忆合金的超弹性变形行为

Superelastic deformation behavior of TiNi shape memory alloy subjected to various cyclic loading

TiNi形状记忆合金由于其优良的机械性能、抗腐蚀能力和生物适应性得到广泛的使用。超弹性是TiNi形状记忆合金重要的力学性能之一。本文通过实验研究了不同加载速率和不同实验温度下承受完全循环加载以及部分加载卸载的Ti Ni形状记忆合金超弹性变形行为。分析了循环变形期间马氏体相变应力和弹性模量变化的特性。研究表明在完全循环加载过程中 ,由于残余应变的存在 ,马氏体相变应力随循环增加而减小。马氏体相变应力的变化量 (即残余应力 )与残余应变成线形关系。对于受过循环变形的机械训练的TiNi形状记忆合金 ,研究了部分加载和卸载情况下其超弹性变形 。

TiNi shape memory alloys are the most commonly used due to their excellent mechanical properties, corrosion resistance and biocompatibility. Superelasticity is one of the important mechanical properties of TiNi shape memory alloy (SMA). In the present paper, the superelastic deformation behavior of TiNi SMA subjected to various full and partial loading with different experimental temperatures and strain rates was investigated. The characteristics of transformation stress and the modulus of elasticity during cyclic deformation were analyzed. The research results show martensite transformation stress decreases with an increase in cycle due to the residual strain during full cyclic loading. The amount of decrease in martensite transformation stress, that was residual stress, was proportional to residual strain. After mechanical training with cyclic deformation, superelastic behavior of TiNi shape memory alloy subjected to partial loading was studied, the starting and completing conditions of the transformation were prescribed.