Effects of grain boundary on slip morphology and dislocation patterns in a fatigued copper bicrystal

Abstract

By TEM technique, the fatigued dislocation structure in copper single crystals have been extensively investigated. Recently, the electron channeling contrast (ECC) technique in SEM has been widely applied to study the dislocation patterns in deformed metals, such as nickel, copper, aluminum and stainless steel. In particular, the SEM-ECC technique has many attractive features, for example, studying the dislocation arrangements over a large area and at some special sites of the specimen, including the vicinity of GBs, deformation bands and cracks. To clarify the GB effect, bicrystal should be regarded as a very ideal model material. In their previous work, the interactions of PSBs with large- and low-angle GBs in copper bicrystal and multicrystal have been investigated. Wherein, the GB was perpendicular to the stress axis and secondary slip was not activated during cyclic deformation of the copper bicrystal. Therefore, the interaction of PSB with GB was relatively simple. Whereas, for the copper bicrystals with a parallel GB, the plastic strain incompatibility was rather serious and secondary slip or multiple slip was often activated near the GB, leading to a GB affected zone (GBAZ) during cycle deformation. In this paper, the effect of GB on slip morphology and dislocation pattern willmore » be further investigated in a fatigued [{bar 1}24]/[{bar 1}27] copper bicrystal with the help of the SEM-ECC technique.« less