FEM modelling of the combined effect of grain boundaries and second phase particles on the flow stress of nanocrystalline metals

► Combined effects of grain boundary and particles strengthening in nano-crystalline metals were modelled by FEM simulations. ► Nanoparticles located at the grain boundaries may contribute to the strengthening process. ► The effect of the particles strongly depends on the relative contribution of grain boundary sliding. ► Particles located at the middle points of grain boundary have a greater strengthening effect than those at triple points. In this study, numerical FEM simulations to provide an insight into the possible combination of grain boundary and second phase particle strengthening in nanocrystalline metals were made. Because grain boundary sliding is one of the major deformation mechanisms in these materials special attention was paid to the role of nanoparticles located at the grain boundaries. It was shown that second phase particles located at the grain boundaries may contribute to the strengthening process, thereby compensating for the loss of strength brought about by grain boundary sliding. However, the effect of the particles strongly depends on the relative contribution of grain boundary sliding to the overall deformation process. In addition, particles located at grain boundaries under conditions of grain boundary sliding significantly influence the distribution of plastic deformation making it more homogenous at the nano-meter scale.