Molecular dynamics modelling of metric scaling effects in nanosized Cu beams holding a grain boundary

Here we investigate the influence from a centrally placed grain boundary in nano-sized beams of Cu subjected to tensile loading normal to the grain boundary. Also the influence of the cross section size of the beams are investigated. The crystallographic orientations in the grains are [100], [110] or [111], and the results are compared to those of single crystal beams. The investigation is performed by molecular dynamic simulations. The Influence of the grain boundary was found to be substantial as compared to single crystal beams, and also the cross section size was found to have a large impact on the results. Introduction of a grain boundary led to plastic initiation and rupture at lower strains than for single crystal beams. Further, only one of the grains in the two-grain beams showed to be preferred as regards dislocation generation and slip. Also a clear correlation between dislocation density and variations in the axial stress-axial strain curve was found.