Superplastic deformation mechanism based on grain boundary dislocation movement

Abstract

A mechanism for superplastic deformation is developed based on experimental data and observations on a high strength Al-Zn-Mg-Cu alloy. In the model the main deformation mechanism is the slip and climb of dislocations along the plane of grain boundaries; the main accommodation process is the slip of dislocations within grains. The deformation rate is controlled by grain boundary diffusion. A relationship between stress and strain rate is deduced. The calculated stress-strain rate and strain rate sensitivity-strain rate curves are compared with the experimental ones. The whole deformation process is described. Some phenomenological features are discussed.