マイクロサイズの銅単結晶試験片の引張圧縮繰り返し変形挙動

抄録

In metals cyclically deformed, the formation of ladder-like dislocation structure brings about the extrusion/intrusion on the surface, which results in fatigue cracking. It is widely known that the pattern size of the ladder-like structure is around a few microns or smaller independently of specimen size. This suggests that low dimensional metals with micro or nanometer scale possess characteristic fatigue behavior because they have no space to form the ladder-like dislocation structure. The purpose of this work is to investigate the cyclic response of a micro-sized copper single crystal specimen which possesses a single slip orientation. In order to apply a tension-compression fully-reversed load to the specimen, we developed a special device, which could grip the specimen end and adjusted the loading axis. The specimen was deformed without cyclic work hardening and a slip localized region, which penetrates the specimen, was formed. The region resulted in intrusions/extrusions on the surface. The TEM observation of the specimen after fatigue showed that the ladder-like dislocation structure does not exist there.