Studies on Formation Mechanism of In Situ Particles During Laser Direct Deposition of Fe-Based Composite Coatings with Valence Electron Structure Parameters

In this study, the formation regularity of C-Cr, C-Fe, and C-Fe-Cr in situ particles during the laser direct deposition of Fe-based composite coatings was theoretically investigated using the phase stability (PS) and phase formation ability (PFA) calculated based on the empirical electron theory of solids and molecules (EET). The calculation results showed that Cr₇C₃, Cr₃C₂, and Fe₃C are more likely to appear during the laser direct deposition of Fe-based composite coatings because they have ideal PS and PFA values in comparison with Cr₃C, Cr₂₃C₆, Fe₇C₃, Fe₂₃C₆, and Fe₄C compounds. The addition of Cr is beneficial for the formation of (Fe, Cr)₃C compounds when the Cr substitution ratio of Fe atoms is within 33.3 pct, whereas it is easier for the (Cr, Fe)₇C₃ and Cr₇C₃ compounds to appear in the alloy coatings when the Cr substitution ratio of Fe atoms is greater than 57.1 pct. These investigation results will provide theoretical guidance for the composition design and performance optimization of in situ particle-reinforced Fe-based composite coatings.