Dubyna V. Thermodynamic Properties of Ternary Ge(Si)-Mn-Al, Ge(Si)-Ga-Y and Al-Ga-Y Melts.

The mixing enthalpies of liquid Si-Mn-Al, Ge-Mn-Al, Si-Ga-Y, Ge-Ga-Y, Al-Ga-Y alloys have been measured by high-temperature isoperibolic calorimetry at 1750 K. All investigated ternary systems are characterized by exothermic mixing heat effects, which increase in order Ge-Mn-Al>Si-Mn-Al>Al-Ga-Y>Si-Ga-Y>Ge-Ga-Y. For all investigated ternary systems the dependence of mixing heats with respect to concentration can be explained on basis of thermodynamic behaviour of boundaries. That is why integral enthalpies and Gibbs free energies of mixing in ternary Si-Mn-Al, Ge-Mn-Al, Si-Ga-Y, Ge-Ga-Y, Al-Ga-Y liquid alloys were calculated using associated solution model. For this purpose the thermodynamic properties of Ga-Y, Al-Y, Si-Y, Ge-Y, Ge-Mn were described using the ideal associated solution model. This model allows to describe available data on mixing enthalpies in the Ga-Y, Al-Y, Si-Y, Ge-Y boundaries with reasonable accuracy. Also using this model the temperature dependence of mixing heats in Ge-Mn boundarycan be expressed and the agreement between different thermodynamics studying of this system can be found. The methodics based on approach proposed by Lukas was developed for calculation of thermodynamic properties of ternary melts. The reasonable agreement has been found between the predicted by the associated solution model and experimental mixing enthalpies. The methods for thermodynamic properties modelling used in present work are valid for all ternary systems formed by two p-metals of III-IV groups Periodic Table and one d-metal. The associate content calculated in this work testifies to presence short range order in investigated melts.