Improving mechanical properties of extruded Mg-Al alloy with a bimodal grain structure through alloying addition

Abstract This paper seeks to find an appropriate alloying method for improving the mechanical properties of wrought Mg alloys that have a bimodal structure of fine and coarse recrystallized grains created through insufficient precipitation. The addition of an alloying element with a high solid solubility in the a-Mg matrix of the base alloy is found to result in a fine, homogeneous grain structure of wrought material through a restriction of grain growth by newly formed fine precipitates. This consequently leads to a significant improvement in strength via enhanced precipitation/grain-boundary strengthening, without any major loss of ductility. However, excessive addition above the maximum solid solubility greatly deteriorates the material's ductility due to the creation of large, undissolved particles. The validity of this approach is demonstrated by varying the addition of Sn to AM80 alloy.