Interfacial bonding between iron and Mo- and Cr-doped tungsten carbides

Abstract

Doping or partially substituting WC with metals, e.g., Mo and Cr, can lower its density while keeping the strength of the modified carbides similar to that of WC, making them attractive as the reinforcement for hardfacing overlays and tool steels, since they can be distributed homogeneously in the metal matrix. However, it is unclear if the doped WC has desirable interfacial bonding with the matrix, e.g., iron. In this study, we investigated the interfacial bonding of Mo- and Cr-doped WC, compared to that of mono-WC, with austenite and ferrite irons via first-principles calculations. (112¯0)Carbide//(110)Fe, (101¯0)Carbide//(100)Fe, and (0001)Carbide//(100)Fe interfaces for both ferrite and austenite with the lowest interfacial mismatch were investigated. Characteristics of the formed interfacial bonds were studied based on the electron localization function, electronic density of states, bond order, and net charge. It was demonstrated that the Mo and Cr-doped WC carbides, (W4−x, M)C4, show comparable or higher adhesive work with iron, compared to that of mono-WC with iron. The metal-substituted or doped W4C4 carbides are promising replacements of heavier WC for tool steels and ferrous hardfacing overlays.