The electronic, mechanical properties and theoretical hardness of chromium carbides by first-principles calculations

Abstract In the present study, the ground state properties of chromium carbides (h-CrC, c-CrC, Cr 3 C, Cr 3 C 2 , Cr 7 C 3 , and Cr 23 C 6 ) are calculated by means of the first-principles pseudopotential method using the CASTEP code. The equilibrium crystal structures and thermodynamical stability of the six chromium carbide phases are discussed. Moreover, the chemical bonding in these carbides are interpreted by calculating the density of states, electron density distribution and Mulliken analysis; all the six chromium carbides have a combination of metallic, ionic and covalent bonding characteristic, while Cr 7 C 3 exhibits the strongest metallic character. The elastic constants, elastic anisotropies and theoretical hardness of the carbides are also presented, which are important parameters for the structural materials and surface coatings.