Dislocation interactions mediated by grain boundaries

Abstract

The dynamics of dislocation assemblies in deforming crystals indicates the emergence ofcollective phenomena, intermittent fluctuations and strain avalanches. In polycrystallinematerials, the understanding of plastic deformation mechanisms depends on grasping therole of grain boundaries on dislocation motion. Here the interaction of dislocations andelastic, low-angle grain boundaries is studied in the framework of a discrete dislocationrepresentation. We allow grain boundaries to deform under the effect of dislocation stressfields and compare the effect of such a perturbation to the case of rigid grain boundaries.We are able to determine, both analytically and numerically, corrections to dislocationstress fields acting on neighboring grains, as mediated by grain boundary deformation.Finally, we discuss conclusions and consequences for the avalanche statistics, as observed inpolycrystalline samples.