A new strain-rate-induced deformation mechanism of Cu nanowire: Transition from dislocation nucleation to phase transformation

Abstract

The plastic deformation mechanism of Cu nanowires is studied using the molecular dynamics simulation method by applying uniaxial tension along the [100] direction at a constant strain rate and constant temperature. At high strain rate and low temperature, we find a new face-centered cubic–body-centered cubic–hexagonal close-packed (fcc–bcc–hcp) phase transformation mechanism, which controls the plastic deformation of the Cu nanowire. If we raise the nanowire’s temperature at a high strain rate, the plastic deformation mechanism will transform from the fcc–bcc–hcp phase transformation mechanism to the well-known momentum-induced-melting mechanism. On the other hand, if we reduce the applied strain rate to a certain level, the plastic deformation mechanism will transform into a dislocation nucleation mechanism. Based on the present study we have proposed a strain rate–temperature plastic deformation map for Cu nanowires. This map tells a vivid story about the transition among the three different plastic deformation mechanisms, and will help us develop a deep understanding of the plastic deformation of Cu nanowires.