Deformation twinning mechanism and its effects on the mechanical behaviors of ultrafine grained and nanocrystalline copper

The role of deformation twinning on the mechanical behaviors of ultrafine grained (UFG) and nanocrystalline (NC) copper was studied under tensile deformation. First, a digital topological model for the numerical simulation on real microstructure was built, in which grain size follows the experimentally observed log-normal distribution. Then, based on the consideration of grain size and loading effect on deformation twinning, a critical twinning stress criterion in NC face-centered cubic (FCC) metals was figured out in this paper, and the finite-element method was applied to determine when and where the deformation twinning would take place in the generated microstructure of UFG and NC copper. Finally, the further deformation behaviors of UFG and NC copper with nanoscale twins was simulated based on the relative definition. Further discussion was presented for prediction results and relative experimental observations.