Atomic simulations of the effect of twist grain boundaries on deformation behavior of nanocrystalline copper

The effects of twist grain boundary (GB) on the mechanical properties of two types of nanocrystalline copper (Cu) under tensile loading are investigated by molecular dynamics simulation. The results indicate that the plasticity of bicrystalline Cu with a high twist angle is much better than that of structure with low twist angle, due to the blockage of dislocations' motion by twist GBs. However, the plasticity of trifurcate crystal Cu is better in low twist angle structure. The studies demonstrate that these different deformation behaviors are associated with the nucleation and propagation of dislocations. The results also show that regardless of crystalline types, the Young's modulus of nanocrystalline Cu slightly increases with increasing twist angle. The general conclusions derived from this work may be of importance in devising high-performance face-center cubic metal with different GBs.