Molecular dynamics study on the equal biaxial tension of Cu/Ag bilayer films

The mechanical behavior, dislocation nucleation and development, and the evolution of interface in Cu/Ag bilayer films during an equal biaxial tension were studied using molecular dynamics simulations. The results show that dislocations are prone to nucleate at the interface of Cu/Ag bilayer film, and then propagate toward the free surface. The deformation defects consist of partial dislocations and intrinsic stacking faults, accompanying with some extrinsic stacking faults and stacking fault tetrahedra which just occur at the interface and propagate in the Cu layer. Compared with Cu and Ag films, Cu/Ag bilayer films have the maximal yield strain. The surface roughness reaches maximum at the yield strain, and then rapidly decreases with the increase of strain. Atoms in stacking faults increase with the strain at the high strain rate, while the rule is reversed at the low strain rate.