Grain refiner fabricated by spark plasma sintering for hypoeutectic Al-Si alloy cast and its refining ability

Grain refiner fabricated by spark plasma sintering (SPS) for an as-cast hypoeutectic Al-Si alloy were proposed. The proposed grain refiner contains Al3Ti and Na flux particles in an Al-11 mass%Si alloy matrix. Through SPS, the grain refiner were obtained without any reaction between the Al3Ti particles, Na flux particles, and Al-11 mass%Si alloy matrix. Casting tests were conducted using the proposed grain refiners, and the refiners reduced the dendrite cell size and the dendrite arm spacing of the primary alpha-Al phase, as well as the lamellar spacing of the eutectic structure. The eutectic Si phase changed to a granular shape upon the refinement of the eutectic structure. Furthermore, the tensile strength and ductility of the as-cast Al-11 mass%Si alloy were drastically improved by adding the proposed grain refiner. This improvement was attributed to the refinement and granulation of the eutectic Si phase.