Molecular dynamics simulation of micro-mechanical deformations in polycrystalline copper with bimodal structures

•We perform molecular dynamics simulation (MD) on the polycrystalline copper with bimodal structures.•We report the different roles of the small grain region and the large grain region, as well as their interaction.•We support stress-strain curves of our bimodal polycrystalline copper samples with different large grain sizes.•We observe partial dislocations first formed in small grains.•We find dislocations can be taken into the large grain region from the small grains region.

Molecular dynamics simulation (MD) was performed on the polycrystalline copper with bimodal structures. As our special grain size distribution based on the inverse Hall-Petch relation, the small grain region and large grain region play different roles in the uniaxial tensile tests. The large grain region imparts the bimodal Cu samples high strength for the lattice dislocations activation. The large grain size effect was studied in this paper. Through our MD simulations, an atomic scale view of the interactions between two regions is also presented with the deformation progress.