低温退火对CuAlMnNi记忆合金晶粒异常长大及超弹性的影响

Effect of Low-Temperature Annealing on Abnormal Grain Growth and Superelasticity of CuAlMnNi Memory Alloy

研究了循环热处理中低温退火对CuAlMnNi记忆合金显微组织及后续晶粒异常长大的影响,并进一步分析了晶粒异常长大对合金超弹性等性能的影响。结果表明,低温退火析出的α相会显著影响后续高温退火时的晶粒异常长大过程,低温退火时析出的α相体积分数越高,则后续高温退火时越容易发生晶粒异常长大,且最大异常晶粒尺寸随着α相体积分数的增加呈现先增后减的趋势;晶粒异常长大会显著改善CuAlMnNi记忆合金的超弹性并降低残余应变,其主要原因是晶界面积的大大减少,导致对于应力诱发马氏体相变的阻碍作用大为降低。

In this paper,the effects of low-temperature annealing on the microstructure and subsequent abnormal grain growth of CuAlMnNi memory alloy during cyclic heat are investigated,and the effects of abnormal grain growth on the superelasticity of the alloy are further analyzed.The results show that the precipitation ofαphase during low-temperature annealing has a significant impact on the abnormal grain growth during subsequent high-temperature annealing.When the volume fraction ofαphase phase is higher,it’s more likely to see the phenomenon of abnormal grain growth during subsequent high-temperature annealing,but the maximum size of abnormal grain increases first and then decreases with the increase ofαphase volume fraction.The abnormal grain growth significantly improves the superelasticity and reduces residual strain of CuAlMnNi memory alloy,which is mainly due to the great decrease of grain boundary area and thus it’s effect on stress-induced martensitic transformation.