Thermodynamic Assessment of the Ho-Tb, Ho-Dy, Ho-Er, Er-Tb, and Er-Dy Systems

摘要

The Ho-Dy, Ho-Tb, Ho-Er, Er-Dy, and Er-Tb phase diagrams are assessed and a thermodynamic database is now available for these systems. The calculated diagrams confirm the hypothesis that solutions of two rare-earth metals not more than two apart in atomic number can be approximated as ideal solutions, while if the difference is more than two, weak interaction parameters are needed. The bcc lattice stabilities for Ho and Er are estimated from intra-rare-earth phase diagram data and extrapolations from existing data for Gd, Dy, and Tb. An attempt to estimate the fcc lattice stability from high-pressure and temperature data was quite difficult but was done for Nd, Pr, and Gd. Moreover, estimates of lattice stabilities for the bcc and close-packed structure sequence of the rare-earth metals are available.