Superplastic behavior of a fine-grained Mg–9Li material at low homologous temperature

Abstract

A fine-grained ($\overline \iota$m) laminate containing 91.0 wt.% magnesium and 9.0 wt. % lithium was prepared by a foil metallurgy technique involving rolling and pressing at low homologous temperature (0.39–0.49 T_m). The processed material exhibits superplastic characteristics above 70 °C (0.40 T_m). The strain-rate-sensitivity exponent is about 0.5 and an elongation-to-failure of 450% was obtained at 100 °C (0.43 T_m). The activation energy for plastic flow in the superplastic region is 65 kJ/mole. This value of the activation energy is related to the expected activation energy for grain boundary diffusion.