Crystal growth mechanism of Si in hypereutectic Al–Si melt during the electromagnetic directional solidification

Abstract

An efficient enrichment of primary silicon from the Al–Si melt can be beneficial for the Si purification and the cost reduction of the solvent refining process. In this paper, an alternating magnetic field was used to enhance the mass transfer and promote the crystal growth of primary silicon during the directional solidification of hypereutectic Al–Si alloy. The results show that the growth rate and morphologies of Si crystals changed continuously along the directional solidification direction. With the decreasing of Si content in the melt and the weakness of the electromagnetic stirring, the crystal growth rate of primary silicon gradually decreased and the Si morphologies changed from plane to cellular, cellular dendrite, and columnar dendrite, respectively. This provides a deeper understanding of the Si crystal growth during the electromagnetic solidification, which will be good for achieving a high-efficiency enrichment of primary silicon in Al–Si melt.