Evading the refining-induced trade-off between performance enhancement and alloy composition deviation in Fe-based amorphous alloys

Abstract

Understanding the slag-metal reactions in Fe-based amorphous alloys is of paramount importance to evade the refining-induced trade-off between performance enhancement and alloy composition deviation. In this study, the B2O3 and B2O3–CaO slags refining-induced alloy composition deviation was theoretically and experimentally verified in Fe83Si2B12P3 (at.%) amorphous alloy, and a quaternary SiO2–B2O3–CaO–Al2O3 slag suitable for FeSiBP amorphous alloy was designed after the careful calculation of slag-metal equilibrium, slag viscosity and melting point. After refining with simple B2O3 and B2O3–CaO slags, the enrichment of B element and depletion of Si element in the FeSiBP amorphous alloy was confirmed due to the oxidation of constituent Si element and the reduction of B2O3 in the slag. The refining-induced alloy composition deviation can be effectively alleviated by using our designed slags, and the 20%SiO2–55%B2O3–10%CaO–15%Al2O3 (wt.%) slag is effective in removing the impurities and enhancing the glass-forming ability (GFA). In terms of the removal of impurities, the high activity of B2O3 in slag is crucial for the oxidation and removal of Mn, Al, Ti impurities. These results are quite vital for the design of refining slags suitable for Fe-based amorphous alloys and pave the way for the large-scale production of high-performance soft magnetic materials.