LAUSR

Abstract To control the superplastic flow and fracture and examine the variation in deformation energy, the stress and grain size of Mg–7.28Li–2.19Al–0.091Y alloy were obtained using tensile testing and microstructure quantification, and new high temperature deformation energy models were established. Results show that the grain interior deformation energy increases with increasing the strain rate and decreases with increasing the temperature. The variation in the grain boundary deformation energy is opposite to that in the grain interior deformation energy. At a given temperature, critical cavity nucleation energy decreases with increasing strain rate and cavity nucleation becomes easy, whereas at a given strain rate, critical cavity nucleation energy increases with increasing temperature and cavity nucleation becomes difficult. The newly established models of the critical cavity nucleation radius and energy provide a way for predicting the initiation of microcrack and improving the service life of the forming parts.