CYCLIC DEFORMATION BEHAVIOR AND FATIGUE CRACK INITIATION IN COPPER BICRYSTALS
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

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.