材料期刊网

In order to reveal the effect of grain boundaries (GBs) on cyclic deformation, the cyclically saturated dislocation patterns within grains and in the vicinity of GBs in a copper bicrystal with a large-angle GB and a copper multicrystal containing small-angle GBs have been observed by the electron channelling contrast technique in scanning electron microscopy. The observations for the multicrystal show that dislocation walls and persistent slip bands (PSBs) can transfer through the small-angle GBs. However, in the copper bicrystal with a large-angle GB perpendicular to the stress axis, PSBs can only form within the component grain with a relatively higher Schmid factor and cannot pass through the GB. From the experimental observations, the effect of GBs on cyclic deformation behaviour is discussed.