CALCULATION OF PHASE-EQUILIBRIA AND THERMODYNAMIC PROPERTIES OF THE LI-NA-H SYSTEM

Available data for the phase diagram and equilibrium hydrogen pressures in the Na - NaH system were optimized to obtain equations for the Gibbs energies of the phases as functions of composition and temperature. Phase diagram data for the Li - Na system were similarly optimized. For the Li - LIH system, optimized Gibbs energy expressions were taken from the literature. The Gibbs energy of ternary liquid Li - Na - H solutions were calculated from these optimized binary Gibbs energies by means of a sublattice model in which the system is treated as a reciprocal ternary system Li - Na - LiH - NaH. Calculated equilibrium hydrogen pressures in the ternary system agree well with available data. Several calculated isothermal sections of the ternary phase diagram are presented.