热处理对NiTi形状记忆合金力学性能的影响

研究了热处理工艺对50.8at%NiTi形状记忆合金力学性能的影响。通过对NiTi合金试样在不同温度下进行固溶处理和时效处理并进行单向拉伸试验,得到试样的屈服强度、抗拉强度、弹性模量和泊松比等力学性能参数。通过光学显微镜对热处理前后试样的显微组织进行观察,估算其晶粒尺寸,并利用Hall-Petch理论分析了试样的晶粒尺寸对屈服强度的影响。研究发现将NiTi合金先进行固溶处理,再进行时效处理,其力学性能改善较为明显。为NiTi 形状记忆合金的工程应用提供了试验依据,有利于扩大该合金的工程应用范围。

Effect of heat treatment on mechanical properties of NiTi shape memory alloy

Effect of heat treatment on the mechanical properties of 50. 8 at% Ni-Ti shape memory alloy undergone solution treatment and aging at different temperatures was studied by conducting unidirectional tensile test to obtain the yield strength,tensile strength,elastic modulus and Poisson’s ratio. The microstructures were observed before and after the heat treatments by metallographic microscope,the corresponding grain sizes were estimated,and the effect of grain size on the yield strength was analyzed based on Hall-Petch theory. The results show that after solution and aging treatments,significant improvement is found in the mechanical properties of the Ni Ti shape memory alloy. The conclusion provides the experimental foundation for the engineering applications of the Ni Ti shape memory alloy and is beneficial to enlarge its application range.