Quasi-static compressive behavior of ultrafine-grained copper at different temperatures

The quasi-static compression experiments of the annealed coarse-grained copper (CG-Cu) and ultrafine-grained copper (UFG-Cu) were performed at temperatures of 77-573 K and strain rate of 10-3 s-1. The results show that, although UFG-Cu displays extremely high flow stress, the ability of strain hardening almost disappears due to the saturation of dislocation density. The sensitivity of strain hardening rate to strain level and temperature is observed to be lower than those of its coarse counterpart. At the same time, the reduction in activation volume due to the grain refinement is the main reason for the enhanced temperature sensitivity of UFG-Cu.