Intrinsic Strengthening of Coherent Twin Boundaries in Copper

Molecular dynamics (MD) simulations were applied to simulate the deformation process of copper with different density of parallel coherent twin boundaries (TBs). It is shown that the strength of perfect copper crystal enhances with increasing coherent TB density. Based on the local hydrostatic pressure analysis, we found that stress concentrations are more likely to form in the interior of the crystal rather than around the TBs. Since the dislocation nucleation is suppressed in the vicinity of the coherent TBs and each TB plane hinders dislocations from propagating, the coherent TBs can be regarded as an intrinsic strengthening phase relative to perfect crystal.