Effect of electromagnetic strengthening on microstructure of precipitates in metallurgical grade silicon

Herein, the effect of electromagnetic strengthening on the microstructures and distribution of precipitates in metallurgical-grade silicon (MG-Si) is investigated with emphasis on analyzing the precipitate composition and transformation at different locations. The results show that almost all impurity elements in MG-Si have a tendency to enrich at the center, which leads to a precipitate at the center of the melt that is much larger and a secondary precipitation phase that is more complex than the edge. Almost all precipitates are composed of FeSi2(Al), Si8Al6Fe4Ca, and FeSi, TiSi, VSi2 composites; however, near the center of the melt, small amounts of Si12Fe5Al4NiZr and FeSi2, TiSi2, VSi2 composite are found. In addition, the enrichment effects of different impurities in the center of melt are compared with the source MG-Si. It is determined that Mn provides the best results because of the higher magnetic moment and scatter distribution, and the effects of Ni, Ca, and V are better than those of Fe, Al, and Zr, which can be explained by the existence of different phases and the theory of clusters. •Microstructure of precipitates in MG-Si were studied by electromagnetic field.•Impurities have a tendency to enrich toward the center.•Secondary precipitation phase of the precipitate at the center is more complicated.