A thermodynamic analysis of the Ta-W-C and the Ta-W-C-N systems

A new thermodynamic analysis of the Ta-W-C system is presented based on the experimental work by Rudy [1] and Rudy and Benesovsky [2]. The Gibbs energ y functions of the following phases were determined: the liquid phase, the fee phase or (Ta,W)(C,N)(x) carbonitride (cF8), and the hcp phase or (Ta,W) (2)(C,N)(x) carbonitride (hP3). Calculated phase equilibria are compared wi th experimental data. The new thermodynamic description of the ternary Ta-W -C system is combined with assessments/predictions of the Ta-W-N, Ta-C-N an d W-C-N systems, and equilibria in the quaternary Ta-W-C-N system are calcu lated. Calculated phase diagrams of all the relevant binary systems are pre sented.