Si purification by enrichment of primary Si in Al-Si melt

The primary silicon crystals and Al-Si alloy in hypereutectic Al-Si melt were separated by electromagnetic stirring and directional solidification. Additionally, the distribution feature of impurities in Al-Si system was verified. The results show that the impurities are mainly located in Al-Si alloy and the grain boundaries between the Al-Si alloy and primary silicon. Furthermore, the morphology of primary silicon changes from fish-bone like to plate like and spheroid due to the different Si contents. The amount of impurities decreases with the increasing of Si content in different positions of the sample. The amount of impurities in the bottom of the sample is approximately 10×10−6, which is obviously improved compared with the 1248.47×10−6 in metallurgical Si.