The present study investigates the effect of different molten metal processing methods on the modification of primary silicon and the microstructure and mechanical properties of hypereutectic Al-18wt%Si alloy. The effects of melt treatment with the addition of electromagnetic vibration, AlCuP, bubbling of argon gas and their combination has been examined and an optimum procedure has been suggested for the treatment of molten Al-Si alloys, which resulted in the finest primary silicon particles with the highest tensile, impact and hardness properties and features of ductile fracture. This optimum procedure includes bubbling of the melt with argon gas for 15 min, the addition of 50 ppm of AlCuP master-alloy and stabilization of the melt for 15 min.
