Induction (high-frequency) boriding of steel was performed at ~1200°C using a novel combined charge of 30 wt % B4C + 70 wt % FeSix (prepared via high-temperature synthesis of Fe2O3/Al/Si thermite mixture). The process conducted below melting points of charge components and substrate yielded 400–600 μm thick multiphase coatings. XRD analysis identified Fe2B, martensitic Fe1.93C0.07, and B(Fe,Si)3 derived from silicon substitution in Fe3B structure. It was demonstrated that these silicide–boride phases achieve a significant hardening effect, with microhardness values between 8770 and 9980 MPa.
Silyakov et al. (Tue,) studied this question.