Abstract:The effects of melt viscosity on the enrichment and separation of Si crystals from Al–Si melt during an electromagnetic solidification process were investigated. Both the enrichment efficiency and the separation were found to be strongly dependent on the melt viscosity. A high melt viscosity was beneficial to the enrichment of primary silicon, whereas a low melt viscosity facilitated the separation process. A new enrichment mechanism was proposed in order to clarify the influence of melt viscosity, and an improved process for achieving high-efficiency enrichment of Si crystals via control of the melt viscosity was also proposed. Additionally, the morphology of Si crystals was found to change from spheroidal to plate-like in shape owing to the difference in viscosities in different regions.

Key words: directional solidification; electromagnetic stirring; Al-Si melt; primary silicon; separation; viscosity