Critical operating stress of persistent slip bands in Cu

This work elucidates the dependence of operating stress of persistent slip bands (PSB) on the channel width and wall dislocation density. Using Cu as a model system and molecular dynamics as the main investigative tool, a new length scale effect, namely the wall dislocation spacing, is provided to enhance theoretical understanding of PSBs. It is discovered that the operation of PSB is a thermally activated event in which operating stress is inversely related to the wall dislocation spacing, strain rate and temperature. Leveraging the existing framework of confined layer slip in nanoscale metallic multilayers and classical nucleation theory, a mathematical model describing the rate- and temperature- dependent PSB operating stress is proposed.