Stress Relaxation and Creep in Nanostructured Copper:Experiments and Simulations

    论文摘要：

    In the present work, stress relaxation and creep tests, high-resolution transmission electron microscopy （HRTEM） and molecular dynamics （MD） simulations were conducted on coarse-grained （cg）， nanograined （ng） and nanotwinned （nt） copper at temperatures ranging from room temperature to 75 °C. The comprehensive investigations provide sufficient information for the building-up of a formula that describes the time, stress, and temperature-dependent deformation and clarify the relationship among the strain rate sensitivity parameter, stress exponent and activation volume. The experimental and simulation results also suggest that under high stress level, dislocation-mediated plastic deformation is predominant in all cg, ng and nt specimens. Under low stress level, the grain boundary （GB） diffusion-associated deformation is dominant in the ng and cg specimens, whereas twin boundary （TB） migration, i.e., twinning and detwinning with parallel partial dislocations, governs the time, stress and temperature-dependent deformation in the nt specimens.

    报告人：张统一