Microstructure evolution and tensile properties of hot rolled Mg-6Al-3Sn alloy sheet at elevated temperatures

A fine-grained (∼3.6 μm) Mg-6Al-3Sn (AT63) alloy prepared by a hot rolled method is subjected to uniaxial tensile tests within the temperature range of 25-250 °C. Mg2Sn and Mg17Al12 precipitates at grain boundaries effectively retard the growth of dynamically recrystallized (DRXed) grains. Grain boundary sliding (GBS) is activated at 250 °C, which is indicated by the stable DRXed grain size and agglomeration of the precipitates at grain boundaries. Moreover, Mg2Sn and Mg17Al12 precipitates promote the formation of dynamic recrystallization (DRX). Both the DRX and GBS result in the high elongation (151.4%) of the AT63 alloy at 250 °C. Results obtained here will shed some light on elevated temperature deformation mechanisms of a new type of Mg-Al-Sn system, which is critical to the development of new Mg alloys with potential for applications at elevated temperatures.