Cu双晶的循环形变行为与疲劳裂纹萌生：Ⅱ.疲劳裂纹萌生与早期扩展

用扫描电镜观察了受应变疲劳载荷作用的Ｃｕ双晶物的表面形貌，发现晶界是疲劳形变双晶是有利的裂纺萌生地点，在滑移带撞击晶界的地方，特别是在几条粗滑移带共同撞击晶界的地方观察到许多疲劳微裂纹；并且发现与平行晶界双晶相比，垂直晶界双晶有有利于疲劳裂纹沿晶界作早期扩展。

CYCLIC DEFORMATION BEHAVIOR AND FATIGUE CRACK INITIATION IN COPPER BICRYSTALS

Surface morphology of fatigued copper bicrystals was investigated by a scan-ning electron microscopy(SEM). It was found that the grain boundaries are the preferred sites for fatigue crack initiation in the fatigued bicrystals. A large number of fatigue microcracks was observed at the sites of grain boundaries where slip bands impinged, especially at the sites where several intense slip bands impinged. And it was found that, compared with the bicrystal specimens with a grain boundary parallel to loading axis, the bicrystal specimens with a grain boundary perpendicular to loading axis are quite favorable for the fatigue crack early growth along grain boundary. A PSB-GB model of fatigue crack initiation can be used to explain the initiation of the intergranular fatigue cracks.