Mechanical properties of nonstoichiometric cubic titanium carbide TiC_y

The changes of elastic constants c_ij in the homogeneity interval from TiC_0.50 to TiC_1.00 of nonstoichiometric disordered cubic titanium carbide are evaluated by a semiempirical method for the first time. It is established that the elastic stiffness constants c_ij of a disordered TiC_y decrease as the titanium carbide composition deviates from stoichiometry. The distributions of the Young's modulus E, the Poisson's ratio μ, shear G and bulk B moduli of monocrystalline particles of cubic TiC_y on the crystallographic direction [hkl] and on relative carbon content y are calculated. The lowest values of G_hkl for TiC_y are observed in the (111) plane. It is found that the deviation of titanium carbide from stoichiometric composition TiC_1.0 is accompanied by increase of the elastic anisotropy. It is shown that the calculated Vickers hardness H_V of titanium carbide on the relative carbon content y increases non-linearly with growing y.