Thermodynamic properties of Si-Y and Ge-Y melts

Using high-temperature isoperibol calorimetry, we have determined the partial enthalpy of mixing of yttrium in Si-Y and Ge-Y melts at 1770 (1780) ± 5 K in the composition ranges 0 < xY < 0.2 (0.4). The results have been used to evaluate the integral enthalpies of mixing for these melts. Their formation has been shown to be accompanied by significant heat release. The mixing enthalpies of the liquid alloys have been optimized using the present and earlier data. The activities of the components of Si-Y and Ge-Y melts have been evaluated from the liquidus coordinates in the corresponding phase diagrams and have been found to exhibit very large negative deviations from Raoult’s law.