Effects of Sc–Er Rare Earth on Solidification Microstructure and Mechanical Properties of A360 Alloy

Hypoeutectic Al-Si alloy (A360) is widely used to high-pressure die casting components used in the aerospace, automobile and building industries. An experimental investigation has been conducted concerning the effect of different rare earth Sc and Er additions on the solidification process of A360 alloy. The results indicate that a precipitation phase Al(Sc, Er)₂Si₂ is formed with the addition of Sc and Er elements. Moreover, the eutectic Si phase evolves from a coarse block-like and irregular polygonal into a granular morphology, and its average size value is decreased from 25.48 μm to 9.46 μm when the content of Sc–Er increases from 0 wt% to 0.6 wt%. In addition, the alloy exhibits an outstanding combination of mechanical and wear resistance properties at a Sc–Er addition of 0.6 wt%. Compared with the unmodified alloy, its ultimate tensile strength has increased from 82.7 MPa to 148.4 MPa and average friction coefficient has decreased from 0.689 to 0.504.