NiTi形状记忆合金的氢致表面损伤

Hydrogen-induced Surface Damage of NiTi Shape Memory Alloy

研究了近等原子比NiTi形状记忆合金在阴极充氢后时效过程中表面的相变与破坏,认为时效裂纹的产生与奥氏体不锈钢类似,为氢释放和氢致马氏体分解导致表面收缩产生较大张应力所致,时效过程中裂纹扩展持续时间超过5天。氢致马氏体微观形貌与应力诱发马氏体相似,二者形貌上不可区分。氢化物与基体的界面和氢致马氏体与奥氏体相界面在时效过程中可能成为裂纹源。

The phase transformation and damage at the surface of near-equiatomic NiTi shape memory alloy were investigated. The results show that similar to ustenitic stainless steel the generation of crack on the surface of NiTi alloy during the aging at room temperature after hydrogen electro-charging is related to the surface stress produced from the hydrogen release and the reducing of hydrogen induced martensite. The growth of crack lasted for more than 5 days. The morphology of stress-induced martensite and hydrogen-induced martensite is similar and could not be distinguished. The interface between hydride and base alloy and the interface between hydrogen-induced martensite and the austenite alloy could be the crack source.