V. S. Sudavtsova

Thermodynamic Properties of Al-Y System Melts

The thermochemical properties of Al-Y melts were determined by isoperibolic calorimetry. It was established that the minimal value of integral mixing enthalpies is equal to −40.8 + 0.4 kJ/mol at 1770 K and xY = 0.41. The thermodynamic properties of liquid alloys were modeled by the developed procedure using the coordinates of a liquidus line in the phase diagram of the Al-Y system, and by the theory of ideal associated solutions. The component activities exhibit high negative deviations from the Raoult law. The Gibbs energies of mixing of Al-Y melts have a minimum of −30.6 kJ/mol at xY = 0.48.

Thermodynamic properties of alloys of the Ni-Sc and Ni-Y systems

Partial and integral enthalpies of mixing for Ni-Y melts at 1775 K (0 < xY < 0.34), 1850 K (0.72 < xY < 1) and Ni-Sc at 1880 K (0 < xSc < 0.35, 0.51 < xSc < 1) are determined by means of calorimetry. Thermodynamic properties of liquid and solid alloys and phase diagrams of Ni-Sc(Y) systems in wide ranges of concentration and temperature are modeled using the ideal associated solution theory. It is found that the activities of components exhibit strong negative deviations from the Raoult’s law.

The thermodynamic properties of Al-Si system melts

The thermochemical properties of Al-Si system melts were determined by an improved isoperibolic calorimetry method. The data obtained correlated with the reliable partial and integral enthalpies of mixing reported in the literature. The method developed was used to model the thermodynamic properties of melts with the use of the liquidus coordinates of the phase diagram of the Al-Si system. The modeled and experimental results were in close agreement with each other.

Thermodynamic properties of liquid alloys Ni-Eu and Ni-Yb

Mixing enthalpies of melts of the binary Ni-Eu (0 < xNi < 0.89) and Ni-Yb (0 < xNi < 1) systems at 1300–1750 K were investigated using the isoperibolic calorimetry. They have alternating signs depending on the melt concentration. With the combined analysis of the data determined by us and in literature, the models of the liquid and solid alloys were obtained, and the phase diagrams were calculated.

Thermodynamic properties of Eu-Pd melts

Partial and integral enthalpies of mixing of melts of the Eu-Pd system were determined by calorimetry at 1300 K in the concentration interval of 0 < xPd < 0.37. It was established that the first partial enthalpy of mixing of Pd was −158 ± 2 kJ/mol. The thermodynamic properties of Eu-Pd melts were simulated according to the theory of ideal associated solutions over a wide interval of concentrations and temperatures. It was shown that the activities of components display strong negative deviations from Raoult’s law, and the minima of the integral Gibbs energies and enthalpies of mixing were found at xPd = 0.65.

Thermodynamic properties of melts of the binary Ag(Au)-Sm systems

The enthalpies of mixing for liquid alloys of the Ag-Sm system are determined by isoperibolic calorimetry at 1450–1506 K in the 0.46 < xSm < 1 range of concentrations. The partial and integral enthalpies of mixing for melts of the Ag-Sm system are obtained over the whole range of concentrations. The activities of components and the entropy of mixing in melts of the Ag-Sm system at 1506 K are calculated using a model of ideal associated solutions (IAS). The partial and integral enthalpies of mixing for melts of the Ag-Sm system, the activities of the components, and the molar fractions of associates in them are calculated using the IAS model. It is concluded that the thermodynamic activities of components in melts of the Ag (Au)-Sm system at 1506 K exhibit great negative deviation from the ideal behavior, and the enthalpies of mixing indicate there are considerable exothermal effects.

Thermodynamic properties of melts of Mn-Sc(Y, Ln) systems

Partial and integral mixing enthalpies of melts of binary systems Mn-Sc and Mn-Y at 1873 and 1830 K, respectively, are determined by calorimetry. It is found that the minima of the mixing enthalpies are −7.1 ± 0.4 and -3.2 ± 0.2 kJ/mol at xMn = 0.60 and 0.61, respectively. The initial partial mixing enthalpies of Sc and Y are −33.2 ± 2.1 and −16.6 ± 0.8 kJ/mol, respectively. The thermodynamic properties of melts of binary Mn-Sc(Y) systems are calculated using the ideal associated solution (IAS) model. It is found that the activities of the components exhibit slight negative deviations from the ideal solutions, and the excess Gibbs energies reach −3.0 and −1.6 kJ/mol, respectively.

Thermodynamic properties of Ni-Ga melts

AbstractThe partial mixing enthalpies of the components (Δm

Thermodynamic properties of alloys of the Co-Sc and Co-Y systems

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