Effect of Sc addition on the microstructure and mechanical properties of as-atomized and extruded Al–20Si alloys

The microstructure evolution and mechanical properties of Al–20Si alloy with Sc addition were investigated after as-atomized and hot-extruded conditions. Microstructural and spectroscopic analyses demonstrate that Sc is enriched at the Si/Al interface. It could be observed that the presence of Sc refined the size of the primary and eutectic Si, without significantly affecting the shape. A considerable improvement in tensile strength, compressive strength, and elongation was observed due to addition in Sc percentage into the composition. The correlation between the microstructure and mechanical behavior strongly indicates that the addition of Sc modifies the Si particles by impurity induced twinning (IIT) mechanisms.

► Microstructure and mechanical properties of Al–Si alloy by Sc addition were studied. ► This study clarifies the mechanism by which Sc modifies eutectic and/or primary Si. ► Sc improved mechanical properties of Al–Si alloy due to reduction in Si size. ► Experimental results indicate that Sc modifies the primary Si by IIT mechanism.