Thermodynamic modeling of the Nb-Si-Ti ternary system

A thermodynamic description of the Nb-Si-Ti ternary system is developed by modeling the Gibbs energies of the individual phases in the system. Due to insufficient experimental data, the ternary description is obtained primarily by extrapolation based on the descriptions of the constituent binary systems, i.e. Nb-Si obtained in this study, Ti-Si and Nb-Ti available in the literature. Nevertheless, the calculated ternary phase equilibria using the thermodynamic description so obtained agree very well with available experimental data, which suggests that the ternary description is reasonable. Although there might be large uncertainties involved in this description for alloy compositions far away from the Nb-Ti boundary binary, it can be very useful, in the absence of experimental data, as a guide for alloy design and processing development. Moreover, it can be used with great advantages in planning phase equilibrium measurements in the future and thus reduce the effort to be expended. (C) 1999 Elsevier Science Ltd. All rights reserved.