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 meth od. Our calculation of the formation energy indicates that the alloy i s stable in the whole range of the carbon concentration x and the maxi mum 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 repla ce carbon atoms and starts to saturate when the nitrogen concentration exceeds 0.5. Trends in the formation energy and bulk modulus are expl ained in terms of the detailed electronic structure of titanium carbon itride. Calculated results are in good agreement with available experi mental data.