Experimental and numerical optimization of the U-ZR-C ternary phase diagram

Abstract

The U-Zr-C ternary-phase diagram is optimized using melting point and vapor pressure data recently measured at Los Alamos National Laboratory and by graphical and numerical curve fitting of self-consistent thermodynamic and phase diagram data reported in the literature. The system is described from 2473 K to 3693 K using isothermal ternary phase diagrams. The solidus and liquidus curves of the U{sub x}Zr{sub 1-x}C{sub y} solid solution were estimated from combined thermodynamic and adjusted phase diagram data. From the solidus and liquidus curves for the solid solution, the reversible heat transferred from the solid to the liquid phase for UC and ZrC were calculated to be 150 and 324 kJ/mol, respectively; and the maximum in the excess free energy for mixing was determined to be on the order of 1100 J/mol at 56% ZrC.