Electromagnetic Stirring Process for Hypereutectic Al-Si Alloys

Effect of electromagnetic stirring on the hyper eutectic Al-Si alloy was studied. The results indicate that after the electromagnetic stirring, acicular or multilateral shape Si becomes tiny, circle, and distributes evenly; acicular and strip second phases break, the distribution also tends to be even. At the same time, the mechanical properties of alloy also improved. When the stirring voltage is 50 V, the stirring effect and the alloy mechanical properties are the best for the hyper-eutectic Al-17.5Si alloy. Along with stirring voltage enhancement and much stronger magnetic field strength, the primary Si and second phases agglomerated, and the mechanical properties decreased. With stirring time extension, primary Si and second phases gradually become tiny and circular; the electromagnetic stirring effect becomes more and more obvious. But when the stirring time is excessively long, the mechanical properties decrease because of the entrapped gas, so the optimal stirring time is 60 s.