Thermodynamic properties and phase equilibrium in alloys of the Eu—Pb system

Firstthe partial and integral enthalpies of mixing of the melts of the Eu—Pb system were determined at a temperature of 1100—1350 K in everything range the composition by method isoperibolical calorimetry. It was established that of the melts of the Eu—Pb system are formed with the release of a big amount of heat: the minimum H = –51,7  ± 0,8 (at xPb = 0,4). Using the model of ideal associated solutions, all the thermodynamic properties (Gibbs energies, enthalpy and entropy of formation of melts, intermetallic compounds and associates) of the Eu—Pb system were calculated. It turned out that the activity of the components in the melts of this system exhibit moderate negative deviations from ideal solutions. According to the IAR model, the temperature-concentration dependences of the Gibbs energies, enthalpies and entropies formation of melts and intermetallics were calculated, and from them were obtained the coordinates of the liquidus curve of the diagram state of the studied system. As a result, the temperature-concentration dependences of the thermodynamic properties of all phases and the liquidus of the Eu—Pb system are obtained, those a thermodynamic description of this system is made. Keywords: calorimetry, melts, intermetallics, thermodynamic properties, Eu, Pb, model of ideal associated solutions, phase equilibria.