“Genes” for material tailoring: Begin with the electron work function for MoC carbide modification—A first-principles study

This article reports a study on the modification of bulk and Young's moduli of MoC carbide by partially substituting Mo with selected metallic elements, which influence the strengths and contributions of covalent, ionic, and metallic bond components to the overall atomic bonding of the carbide and thus its mechanical properties. Electron work function (EWF) analysis demonstrates that this parameter plays a promising role as an indicator similar to an encoded parameter with material “genetic” information for guiding the substitute selection. The higher the carbide's EWF, the higher are its bulk and Young's moduli. A substitute having a higher EWF generally enhances the covalent bonding at the expense of ionic bonding. The covalent bond plays a primary role in determining the carbide's strength, while the ionic bonding also contributes to the strength to some degree. A substitute having a higher EWF enhances the metallic bonding, which improves the carbide's strength as well, although such a contribution is minor.