摘要
利用长距离显微镜(ＱＲＭＳ)对经过精细抛光的试样表面进行观察．原位研究了ＴｉＮｉ形状记忆合金中应力诱发马氏体相变(ＳＩＭＴ)和逆相变对疲劳行为的影响．包括对应力－应变响应和疲劳裂纹萌生和裂纹扩展规律的影响、并与普通金属的疲劳行为进行了对比．结果表明:ＴｉＮｉ形状记忆合金中可逆的应力诱发马氏体相变有利于改善疲劳性能、然而也正是反复发生的ＳＩＭＴ引起的滑移导致了疲劳裂纹的萌生．此外．在实验中还观察到若干反常的疲劳行为．如恒△Ｋ加载时裂纹扩展速率对裂纹长度的依赖性、裂纹扩展时的分叉以及疲劳试样表面出现的大量二次裂纹等现象．
The in situ investigation of the effects of stress induced martensitic transformation (SIMT) on fatigue behavior in TiNi shape memory alloy (SMA) was conducted using a quester remote measurement system (QRMS). The effects of SIMT on stress-strain response, crack initiation and propagation of fatigue were investigated. Being compared with normal alloys, the result shows that the reversible SIMT improved the fatigue properties, but it also is the cause resulting in the slip which leads to the crack initiation. Some abnormal behaviors in SMA were discussed, such as the dependence of propagation rate to crack length in constant △K control fatigue tests, the phenomenon of crack branches and secondary cracks etc.
出处
《金属学报》
SCIE
EI
CAS
CSCD
北大核心
2002年第6期575-582,共8页
Acta Metallurgica Sinica
基金
国家自然科学基金50001012
国家重点基础研究发展规划G19990650项目资助
