Enhanced plasticity and creep in an extruded Mg-Zn-Zr alloy

Creep and superplasticity were investigated by testing in tension a fine-grained extruded Mg-Zn-Zr Mg alloy in the temperature range 100-300 °C. Analysis of the experimental data suggests that grain boundary sliding becomes the dominating mechanism at 200 °C, leading to a true superplastic behaviour. By contrast, for lower temperatures, the straining process is controlled by dislocation climb. A comprehensive model, taking into account the simultaneous operation of the different mechanisms, was used to describe the dependence of strain rate on the applied stress.