DFT investigation of physical properties and electronic structure of metastable cubic CrC partially substituted with transitional metals

Abstract

Mechanical strength and wear resistance of chromium carbides are relatively low compared to other transition metal (TM) carbides, such as TiC or WC. However, carbides can be tailored by partially substituting their host metal elements with other TMs. In this computational study with first-principles calculations, we investigated the effects of TMs on the stability and properties of metastable CrC carbide having a face-centered cubic structure. It is demonstrated that most TMs in IV and V groups can improve the thermodynamic stability of CrC with negative formation energies, meaning that such TM-substituted CrC can be formed using equilibrium or near-equilibrium synthesis routes. Mechanisms for the improved stability and mechanical properties of CrC by TM substitution were investigated through analyzing corresponding changes in the density of states, charge density distribution, and Bader charge. It is shown that the improved stability and properties of TM-substituted CrC result from changes in the distributions of covalent, ionic, and metallic bonds. TM-substituted CrC carbides with different densities provide more alternatives or options for widened applications of the Cr carbide family.