Structural and electronic properties of chromium carbides and Fe-substituted chromium carbides

Chromium carbides are coated over base metal (Fe) to increase wear and corrosion resistance. The electronic structure and bonding properties for chromium carbide bulk phases (Cr₃C₂, Cr₇C₃ and Cr₂₃C₆) and Fe-substituted chromium carbides is investigated using Density Functional Theory (DFT). The bonding in these carbides has been interpreted in the form of partial density of states, electron density distribution and Mulliken population method. Cr₃C₂ exhibits the strongest covalent character while Cr₇C₃ displays the highest metallicity. Cr₃C₂ showed the highest stability among the chromium carbide phases. In the Fe-substituted chromium carbides (Cr₂FeC₂), the site preference of Fe in Cr₃C₂ system has been reported. In Fe-substituted chromium carbides also show both of metallic and covalent character and Cr₂Fe3C₂ is found to be the most stable Fe-substituted chromium carbide system.