A rate dependent constitutive model for ECAE Cu based on instrumented nanoindentation results

We have investigated the plastic deformation behavior, especially the strain rate sensitivity of Cu, subjected to severe plastic deformation via equal channel angular extrusion (ECAE) with a varying number of passes. We have performed nanoindentation strain rate jump experiments to measure the hardness values at different loading rates, and determine the strain rate sensitivity (SRS). In turn, the activation volume (V⁎) associated with plastic deformation of the ECAE Cu has been derived and analyzed. Based on the dislocation-mediated processes during ECAE, including dislocation accumulation, dynamic recovery and recrystallization, combined with creep theory, a strain rate dependent constitutive model has been constructed for the ECAE Cu. We have reached good agreement between the model predictions and the experimental results. It was found that the model can provide a plausible understanding of the various aspects of the mechanical behavior of the ECAE Cu.