Direct observation of dislocations originating from perfect twin boundaries

This paper addresses the plasticity deformation mechanisms caused by nanoindentation of pre-existing coherent twin boundaries (CTBs) in copper using atomistic simulation. Initial plasticity caused by the homogeneous nucleation of threefold symmetry twinning partial loops is observed below the critical twin lamella length of 2.50 nm, accompanied by a significant reduction in critical pressure, which indicates that dislocations can originate from perfect CTBs. However, the CTBs will block the dislocation motion following mechanism of twin boundary migration, resulting in further plastic deformation.