Cyclic deformation and dislocation structure evolution of a copper bicrystal with components rotating gradually along the grain boundary

Abstract

The push-pull cyclic deformation of a copper bicrystal with components rotating gradually along the grain boundary (GB) was carried out under constant plastic strain amplitude at room temperature in air. The evolution of slip morphology and dislocation structure was observed by scanning electron microscopy electron channelling contrast technique. It was shown that slip morphology and dislocation structure in one of the grains changed gradually along the GB. This phenomenon can be understood based on the local irreversible rotation of crystals, which exists during the symmetrical push-pull loading. When the secondary slip was localized to form the secondary persistent slip bands, which interacted with the regular walls in the second type of deformation band, then the cell structure was formed. The second type of deformation band is one kind of sites for cell formation.