A study of the formation of Ti(CN) solid solutions

The phase stability of Ti(CN) solid solutions was investigated based on the accurate first principles method, the Debye model and the rigid band model beyond a simple ideal mixing model. The Gibbs free energy of formation was calculated using the results from the above models and the standard stale energies for the formation of pure TiC and TiN from JANAF tables at varying temperatures. The predicted phases for highest stability at 1700 and 2100 K are in the range of 0.6 and 0.3, whereas those obtained experimentally we re near 0.7 and 0.4 nitrogen contents at 1700 and 2100 K, respectively. Fro m the calculation results it can be safely concluded that Ti(CN) solid solu tions have higher stability than that predicted by the ideal mixing model. (C) 1999 Acta Metallurgica Inc. Published by Elsevier Science Ltd. All righ ts reserved.