Microstructure and Mechanical Property Correlation of Mg-Si Alloys

The present work aims at understanding the microstructure and mechanical property correlation of hypo (Mg-0.5, 0.7, 1.15 wt% Si) and hyper (Mg-2, 4, 6, 8 and 10 wt% Si) eutectic binary Mg-Si alloys. The microstructures of hypoeutectic alloys consist of α-Mg and lamellar Mg-Mg 2 Si eutectic phases; whereas the microstructures of hypereutectic alloys consist of primary Mg 2 Si, Chinese script eutectic Mg 2 Si and α-Mg phases depending upon the Si content. Significant increase in hardness values of these alloys was observed as a function of Si content which is due to the presence of hard Mg 2 Si phase. In the hypereutectic alloys, the average microhardness of primary Mg 2 Si was about ten times higher than that of α-Mg. Compressive behaviour, tensile properties (UTS, YS and %E) at the room temperature (RT) as well as at 150 °C, elevated temperatures (ET) were analyzed and reported as follows: compressive strength of Mg-Si alloys has improved with the increase of Si content, Mg with 2 to 4 % Si shows good tensile properties at RT and ET. Alloys containing high Si content show a marginal reduction in strength at high temperatures due to the presence of the thermally stable Mg 2 Si. Graphical Abstract