A dual deformation mechanism of grain boundary at different stress stages

• A dual deformation mechanism of an asymmetric grain boundary was reported.
• Grain boundary with non-planar structure was found to show a high ductility.
• Migration of the asymmetric grain boundary was observed.
• The evolution and motion of grain boundary was correlated to dislocation activity.

Molecular dynamics (MD) simulation with embedded-atom method (EAM) potential was carried out to study the structure and shear response of an asymmetric tilt grain boundary in copper bicrystal. A non-planar structure with dissociated intrinsic stacking faults was observed in the grain boundary. Simulation results show that this type of structure can significantly increase the ductility of the simulation sample under shear deformation. A dual deformation mechanism of the grain boundary was observed; the grain boundary can be a source of dislocation emission and migrate itself at different stress stages. The result of this study can provide further information to understand the grain boundary mediated plasticity in nanocrystalline materials.