Thermodynamic evaluation of phase equilibria in the ternary Cu-Cr-Ni system

The phase diagram in the ternary Cu-Cr-Ni system was calculated by a Calphad method. The molar Gibbs energy was expressed by a subregular solution model for the face-centered cubic (fcc) phase, the body-centered cubic (bcc) phase and the liquid (L) phase. The ternary interaction parameters of the fcc phase were evaluated on the basis of the observation in a previous study for phase equilibria in the ternary Cu-Cr-Ni system. The observation indicates that the miscibility gap exists at temperatures of T = 1073 and 1273 K for the fcc phase in the ternary Cu-Cr-Ni system, though the complete solid-solution phase is stable at T = 628-1358 K for that in the binary Cu-Ni system. As a result, the three-phase region of the fcc Cu-rich (alpha(1)), fcc Ni-rich (alpha(2)) and bcc Cr-rich (beta) phases appears at T = 1073 and 1273 K. The observation is satisfactorily reproduced by the calculation. According to the calculation, the invariant reaction L + alpha + L+ alpha(1) + alpha(2) occurs at T = 1487 K and that L + alpha(2) -> alpha(1) + beta takes place at T = 1402 K. (c) 2006 Elsevier B.V. All rights reserved.