Numerical exploration of plastic deformation mechanisms of copper nanowires with surface defects

Based on the molecular dynamics simulation, plastic deformation mechanisms associated with the zigzag stress curves in perfect and surface defected copper nanowires under uniaxial tension are studied. In our previous study, it has found that the surface defect exerts larger influence than the centro-plane defect, and the 45° surface defect appears as the most influential surface defect. Hence, in this paper, the nanowire with a 45° surface defect is chosen to investigate the defect’s effect to the plastic deformation mechanism of nanowires. We find that during the plastic deformation of both perfect and defected nanowires, decrease regions of the stress curve are accompanied with stacking faults generation and migration activities, but during stress increase, the structure of the nanowire appears almost unchanged. We also observe that surface defects have obvious influence on the nanowire’s plastic deformation mechanisms. In particular, only two sets of slip planes are found to be active and twins are also observed in the defected nanowire.

► Perfect and surface defected nanowires under tension are thoroughly simulated.
► Plastic deformation mechanisms for zigzag stress curves are carefully explored.
► Stress decrease regions are accompanied with SFs’ generation and migration.
► The nanowire’s structure remains unchanged within stress increase regions.
► Obvious influence on deformation mechanisms is found due to surface defects.