The inelastic deformation of hierarchically nanotwinned copper that is composed of primary and secondary twins under indentation and scratch has been investigated by using large-scale molecular dynamics simulations. Simulation results show that the partial dislocation activities are the main factor that dominates the inelastic deformation. Both the indentation and scratch processes show arrest and burst behaviors of partial dislocations, which indicates that the twin boundaries have a template effect on the inelastic deformations. Moreover, it is found that the characteristic size of the inelastic deformation zone increases, respectively, with the increase of the primary and secondary twin spacings.
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