STRESS-DRIVEN SHEAR-COUPLED MIGRATION OF HIGH-ANGLE GRAIN BOUNDARIES IN METAL-GRAPHENENANO COMPOSITES

A theoretical model is suggested which describes plastic flow through stress-driven shear-coupled migration of high-angle grain boundaries (GBs) in metal-graphene nanocomposites. In the framework of the suggested model, stress-driven shear-coupled GB migration gives rise to the formation of wedge disclinations at GB junctions and edges of graphene inclusions. Energy and stress characteristics of stress-driven shear-coupled GB migration are calculated (in the exemplary case of Al-graphene nanocomposite). It is found that graphene inclusions strengthen metal-graphene nanocomposites. This is well consistent with experimental data reported in literature. Also, it is revealed that graphene inclusions in metal-graphene nanocomposites either hamper or enhance unstable GB migration and thereby grain growth driven by stress, depending on inclusion length. It is shown that shear-coupling effect provides more pronounced strengthening of nanocomposite and additional hampering of unstable GB migration compared to normal migration without a coupling shear.