Correlating structure and orbital occupation with the stability and mechanical properties of 3d transition metal carbides

The development of novel transition metal carbides for improved hard coating technologies requires a detailed understanding the factors influencing their stability and mechanical performance. To this end, we carried out first principles calculations based on density functional theory to tabulate electronic structures, formation energies, phonon dispersion curves 3d adopting zincblende, rocksalt, cesium chloride structures. By analyzing corresponding results, outline theoretical framework that describes how valence electron concentration bonding configuration control these compounds. Many early are predicted be stable in rocksalt zincblende enabled by filled states, whereas structure shows persistent instability. For compounds stable, properties were investigated through calculation elastic tensors, from which observable including Vicker’s hardness ductility derived. A robust performance is shown correlated with complete filling orbitals as illustrated TiC VC, have calculated hardnesses 25.66 22.63 GPa respectively. However, enhanced toughness can achieved allowing partial occupation antibonding states CrC, has relatively low Pugh’s ratio 0.51.