A New Strategy for a Combination of Permanent Magnet Stirring and La–Ce Addition Toward the Solidification of A356 Aluminum Alloy

A356 aluminum alloy has attracted enormous attention because of its excellent mechanical properties and good corrosion resistance. Refining the eutectic Si phase is required to improve the mechanical properties for practical applications. In this work, a new strategy is proposed by synergizing the permanent magnet stirring (PMS) with rare earth (RE) La and Ce elements simultaneously during the solidification of A356 aluminum alloy. Experimental studies reveal that the eutectic Si phase transforms from coarse needle-like and flake-like shapes to small granular morphology, and its average size reduces from 12.94 to 8.86 μm. It is noted that the additions of La and Ce can induce twins and stacking fault structures in the Si phase preventing its further growth. Meanwhile, the PMS can significantly refine the grain size of α-Al phase and generate more small size La–Ce precipitates at the front of Si phase. When PMS and rare earth are applied together, the electromagnetic force generated by PMS and the twins and stacking fault structures induced by rare earth elements La and Ce, collectively act on the A356 alloy to refine both the Si phase and α-Al phases. The refined alloy exhibits an outstanding combination of mechanical properties and wear resistance.