Grain refinement mechanism in an Al-Si-Mg alloy with scandium

► Scandium can be used to refine aluminum grains in an Al-Si-Mg aluminum alloy. ► The effectiveness of Sc is lower than that of conventional Al-Ti grain refiners. ► Al3Sc particles can act as heterogeneous nuclei of aluminum phases. ► Higher alloying elements cause more intermetallic compound phases. ► Those phases cannot effectively act as heterogeneous nuclei compared with Al3Sc particles.