Study on the mechanical properties of gradient grains based on molecular dynamics

This study used molecular dynamics simulations to investigate the plastic deformation mechanisms of gradient nano-grained (GNG) copper. The results show that GNG structures have higher yield stress compared to uniform nanocrystalline structures, with the g = 0.30 model exhibiting a significant increase in flow stress. GNG structures can effectively distribute atomic stress, transferring it from coarse grains to fine grains and reducing local stress concentration. Coarse grains undergo severe shear deformation, while grain boundary (GB) activities transition from migration in coarse grains to rotation in fine grains. GNG structures enhance the ability to coordinate deformation through GB motion, suppress dislocation formation, and facilitate interactions between dislocations and GBs, thereby improving strength and toughness.