Underlying mechanisms of drastic reduction in yield asymmetry of extruded Mg-Sn-Zn alloy by Al addition

This study demonstrates that the addition of Al to the Mg-7Sn-1Zn alloy significantly reduces the tension-compression yield asymmetry of the extruded alloy and that this reduction is strongly related to the variation in the area fraction of deformed grains that do not undergo dynamic recrystallization. The decrease in the amount of these grains by Al addition has adverse effects on the improvement in the tensile yield strength but beneficial effects on that in the compressive yield strength. The relationship between the microstructural characteristics of deformed grains and the yield strengths of the extruded alloy is discussed herein.