Thermodynamic modeling of the U-Nb-Zr ternary system

Abstract

Based on a critical evaluation of experimental phase diagram data in the literature, the U-Nb-Zr ternary system has been assessed using the CALPHAD technique for the first time. The individual solution phases, i.e. liquid, bcc, ort, tet, and UZr2, have been modeled. The modeling covers the whole composition range and a wide temperature range from 450 to 2300 °C. A set of self-consistent thermodynamic parameters have been developed. Comprehensive comparisons between the present calculations and measured phase diagrams show that the reliable experimental data are well accounted for by the present thermodynamic description. With regard to the bcc-γ phase, the miscibility gaps and related phase relations are satisfactorily reproduced by the present calculation. Based on this, the solvus projection and reaction scheme of the U–Nb–Zr system have been generated, thereby providing guidance for possible industrial applications.