高密度パルス電流印加による純銅の疲労損傷発達に及ぼす影響とそのメカニズムの解明

抄録

It is important to improve fatigue characteristic of metallic materials to prolongate fatigue life. In this study, high current density electropulsing was applied to polycrystalline copper, and its effect on the formation and growth of Persistent Slip Band (PSB) was evaluated. Specimen was subjected fatigue loading conducted by displacement control. Using replica method, extrusion formed on specimen surface was observed. High current density electropulsing was conducted when arbitrary fatigue test had accomplished. After each cycle, the differences in growth of extrusion with and without the application of electropulsing were observed using Atomic Force Microscopy (AFM). As a result, it was turned out to be that electropulsing has following effect; (1) extrusion growth delays (2) extrusion height decreases. Polák’s vacancy model was applied to these experimental results. Electropulsing causes acceleration of vacancy diffusion existing channel of PSB towards PSB wall or matrix vein. Reduction of vacancy concentration induces suppression of atomic flux from PSB channel to matrix vein until vacancy concentration leads to its saturation again. It is thought that in this duration, extrusion growth keeps suppressing.