Effect of Sc microalloying addition on microstructure and mechanical properties of as-cast Al-12Si alloy

The effect of microalloying 0.1 wt% Sc on microstructure and mechanical properties of as-cast Al-125i (wt.%) alloys was investigated. Sc refines alpha-Al grain average size from 400 mu m to 135 mu m and eutectic Si average size from 4.6 mu m to 0.7 mu m, and modifies Si from plate-like shape to fibers as well. The microaddition of Sc also leads to the formation of coherent nanosized Al3Sc precipitation and other Sc containing intermetallic phases with a length < 10 mu m. The tensile strength increases from 183 MPa of the base alloy to 254 MPa of the Sc-modified alloy, and the elongation increases from 3.5% to 8.3%, respectively. Moreover, this Sc-modified alloy has a retention of 85% strength even after thermal exposure at 350 degrees C for 160 h.