Microstructure evolution of precipitates during solidification in metallurgical grade silicon

Abstract

Understanding the microstructure evolution of precipitates in metallurgical grade silicon (MG-Si) has vital research significance and industrial application. In this work, the evolution of precipitate distributions and morphology was systematically investigated in silicon during cooling through the quenching process. The results show that the micro-segregation of precipitates is mainly concentrated in the early stage of solidification, but microscopic segregation persists in the solidification stage. Al element was confirmed in the FeSi2(Al) phase in the form of dissolved Al. The Al content increases with the extension of the solidification time, but generally does not exceed 10%. The Si8Al6Fe4Ca phase gradually becomes more concentrated during the solidification process. Some of the V element in the FeSi2Ti(V) phase gradually separated into the FeSi2Ti phase during the solidification process, and the rest of the V element transformed into TiSi2 and VSi2 mixed phase. The Si–Fe–Al phase gradually increased and eventually evolved into the Si7Al8Fe5 and Si6Al9Fe4 phases with further solidification.