Observations on persistent slip bands transferring through a grain boundary in a copper bicrystal by the electron channelling contrast in scanning electron microscopy technique

Abstract

To reveal the interaction of persistent slip bands (PSBs) with grain boundaries (GBs), a specially designed [134]/[18 2 7]copper bicrystal with a tilting GB and a common primary slip plane in its component crystals was prepared. The dislocation patterns within grains and near the GB in the copper bicrystal cyclically deformed at axial plastic strain amplitude of 0.9 10-3 were observed by the electron channelling contrast in scanning electron microscopy technique. The observation results show that the surface slip bands can transfer through the GB in the copper bicrystal continuously and do not induce any secondary slip near the GB. The ladder-like PSB structures can form in both [134] and [18 2 7] component crystals. On one surface, the ladder-like PSBs are still continuous beside the GB; however, the dislocation arrangements in those PSBs beside the GB become irregular and discontinuous on another surface. In addition, on the common primary slip (111) plane, a dislocation-affected zone with a width of 5-10mum was observed on one side of the GB. Those observations reveal that the dislocation structures within the surface slip bands transferring through the GB in the copper bicrystal are not completely continuous during cyclic deformation even though the two grains have a common primary slip (111) plane.