Tensile Deformation Behaviors in a Fine-Grained, Rolled Mg-3Al-3Sn Alloy at Room Temperature up to 250 °C

Uniaxial tensile tests were performed on fine-grained, rolled AT33 alloy at strain rates of 1.0 x 10(-4) -1.0 x 10(-1) s(-1) and temperatures of 25-250 degrees C. The rolled AT33 alloy with an average grain size of 7 mu m was produced by cast-rolling and hot-rolling. The relative deformation mechanisms at high temperature were investigated in this study. It was found that the strain rate sensitivity increases from 0.01 at room temperature to 0.13 at 250 degrees C. The average stress exponent and the activation energy have been calculated to be 6.5 and 145 kJ mol(-1), respectively, indicating that the dominant tensile deformation mechanism is dislocation climb-controlled creep profiting from the lattice self-diffusion. The dispersed nano-sized Mg2Sn particles in the rolled AT33 alloy increase dislocation accumulation, which not only contributes to a promising tensile strength at high temperature but also provides a high driving force for the dynamic recrystallization (DRX). It has found that DRX is mainly responsible for the obtained high tensile ductility of 76-205% at temperatures of 200-250 degrees C.