Refining of metallurgical grade Si by solidification of Al-Si melt under electromagnetic stirring

Aiming at developing a Si solidification purification process in the Al-Si alloy system, series of experiments on the effect of electromagnetic stirring on refining of metallurgical grade Si(MG-Si) were carried out. By the use of electromagnetic stirring, an increase of size and average mass of primary Si flakes with the increasing voltage of the electromagnet were obtained. Impurity elements formed intermetallic compounds with Al and Si, such as Al7Fe2Si(α phase) and Al5FeSi(β phase). An intermetallic compound type transformation with electromagnetic stirring was observed. The refined Si under the alternative electromagnetic field contains much lower B and P than those without the electromagnetic stirring. An apparent segregation coefficient was introduced to describe the segregation between solid Si and Al-Si melt. The apparent segregation coefficients of B and P are determined to be 0.37 and 0.17, respectively, when the voltage of the electromagnet is 210 V and cooling rate is 0.5 K min−1.