Design of a novel Si-Fe-Ca alloy with enhanced Ca yield for silicon steel refining: Tailoring phase composition and thermodynamic stability

To enhance the calcium yield during calcium treatment of non-oriented silicon steel, a novel Si-Fe-Ca alloy is designed and prepared using commercial FeSi, Si-Ca alloy, and silicon steel scrap. The influence of Fe content on elemental yield, phase characteristics, physicochemical properties, and calcium-treatment efficiency is systematically investigated. The obtained results show that the yields of Si and Ca elements exceeding 85% in the prepared Si-Fe-Ca alloy. Low-Fe alloys (S1, S2) primarily consist of Si, FeSi 2 , and CaSi 2 phases. With increasing Fe content (S3–S6), the dominant phase changes from Si to FeSi, accompanied by refined Si phase, coarsened FeSi and finely dispersed CaSi 2 in the matrix. Thermodynamic calculations indicate that although higher Fe content raises Ca activity, it remains below 0.0008 (