Electronic structure and structural stability of TiCxN1-x alloys

We have investigated the structural stability and elastic stiffness of TiCxN1-x alloys using the ab initio pseudopotential total-energy method. Our calculation of the formation energy indicates that the alloy is stable in the whole range of the carbon concentration x and the maximum stability is obtained for 0.5 less than or similar to x less than or similar to 0.75. The bulk modulus increases as nitrogen atoms replace carbon atoms and starts to saturate when the nitrogen concentration exceeds 0.5. Trends in the formation energy and bulk modulus are explained in terms of the detailed electronic structure of titanium carbonitride. Calculated results are in good agreement with available experimental data.