Leszek A. Zabdyr

Thermodynamic study and the phase diagram of the Mg-Sn system

By means of concentration cells of the following type, Mg (l)MgCl2 in (LiCl-KCl)eut (l)Mg-Sn (1), the partial thermodynamic data of Mg in Mg-Sn liquid solutions have been obtained in the composition range of 0.1 ≤XMg ≤ 0.75 and at temperatures from 950 to 1100 K. These values are compared with thermodynamic data reported in the literature and used for the evaluation to obtain a complete set of thermodynamic functions for phase diagram calculations and for further interpretation by the associate model. This model, which accepts the existence of ‘Mg2Sn as-sociates’ in the liquid alloys, enables calculations of viscosity by Kucharski’s method corre-lating properly with experimental data. Mutual correlations between thermodynamic properties, physical properties, structure, and the phase diagram of the Mg-Sn system were shown to in-dicate a maximum chemical short-range order close to the composition Mg2Sn.

Phase equilibria in the cobalt oxide-copper oxide system

Thermodynamic properties were determined for the system cobalt oxide-copper oxide by means of an electromotive force (EMF) measurement techniques using galvanic cells with calciastabilized zirconia (CSZ) as the solid electrolyte and with air as the reference electrode according to the following schemes: CuO, Cu2O | CSZ | air and CoO-CuO, Cu2O CSZ | air for composition variables y=XCu/(XCo+Xcu equal to 0.05, 0.15, 0.25, 0.35, 0.45, 0.667, and 0.8; and within the temperature interval 1200–1350 K. Thermodynamic properties calculated directly from EMF values were combined with the available literature data on phase equilibria, and thermodynamic properties of solid phases in the Co-Cu-O system were assessed. Both terminal solid solutions, (Co,Cu)O and (Cu,Co)O, were described by a sublattice model with Redlich-Kister excess term. The interaction parameters for both (Co,Cu)O and (Cu,Co)O solid solutions and the Gibbs energy of formation for the intermediate phase Cu2CoO3 were obtained. The Gibbs energies of fictive end-members: monoclinic “CoO” and “CuO” with rock salt structure were derived as well. The phase diagrams were calculated using the assessed thermodynamic parameters. The (T, y) phase diagram was calculated for existence under ambient air. The property diagrams log10P(O2) versus composition and activity of CuO versus composition were calculated at 1273 K. The results of our calculations were in a good agreement with available experimental data.

Phase equilibria in ternary Cd-Sb-Zn system

Abstract Both the authors and literature data on phase equilibria in ternary Cd-Sb-Zn alloys were carefully analyzed and, selected and thermodynamic functions of ternary phases were optimised by TER-GSS. Phase equilibria calculations were performed by ThermoCalc resulting in invariant reactions parameters, liquidus surface and a number of vertical and isothermal sections of the system under investigation. Metastable tendency was explained by using of Cd-Sb system as an example.

Thermodynamics and phase equilibria in the Sb-Zn system. Critical assessment

Abstract Thermodynamic and phase diagram data were assessed and then optimized by Lukas method. Phase diagram calculations were performed using two alternative descriptions for the liquid and results were compared with the available experimental data. Phase diagrams are presented for both models and Redlich-Kister description is suggested as more useful in case of such complicated system.

A new thermodynamic study of the liquid Sb-Zn and Cd-Sb-Zn alloys

A unique behavior observed in one of the thermodynamic studies on liquid Sb-Zn alloys is a distinct curvature on the emf vs temperature plots at some compositions, indicating nonzeroΔCp values and revealing some ordering tendencies in the liquid. To confirm or negate the existence of this feature and to determine whether it is transferred to the ternary system, emf measurements were made in liquid Sb-Zn and Cd-Sb-Zn alloys. Ninety-six compositions were investigated through the temperature range from liquidus up to 650 °C; a curvature on emf vs temperature plots was found in thirty-seven cases. A computer program was written to calculate thermodynamic functions for ternary alloys and a part of the liquidus surface by the modified Flengas-Pelton method. Comparison with the available experimental data shows satisfactory agreement, the curvilinear behavior in the Sb-Zn system transfers to ternary alloys.

Cd-In (cadmium-indium)

The assessed coefficients agree extremely well with existing experimental data. The liquid, fee, bet, and cph phases of the Cd-In system are satisfactorily represented by Redlich-Kister polynomial expressions to describe the Gex. G^In is best represented as a Wagner-Schottky-type, two sublattice phase where the defects are antistructure atoms, i.e., (Cd, In)o.75(In, Cd)o.25-With these descriptions, the resulting optimized coefficients for the Gex expressions reproduce the known experimental phase diagram within experimental error. There is also excellent agreement between the measured and calculated thermodynamic quantities.

Electromotive force measurements in liquid Ag-In-Pd lead-free alloys

Abstract Emf technique was employed to determine indium activities in the liquid Ag-In-Pd alloys using galvanic cells with yttria-stabilised-zirconia as solid electrolyte according to the scheme: kanthal/rhenium, Ag-In-Pd, In 2 O 3 | YSZ | Ni, NiO, Pt. Composition and temperature measurement ranges were limited, because of very steep liquidus surface; 35 compositions for X PD up to 0.3 were investigated and at temperatures from near-liquidus up to 1700 K. High temperature experiments required special moly furnace to be constructed with unique automatic gas supply system for furnace winding protective atmosphere. Emf readings were taken and recorded by automatic data acquisition system. Linear dependence of emf on temperature was observed for all compositions investigated, and results were approximated by straight line equations. Then In activities were calculated using well-known relations and taking into account correction for thermoelectric power between kanthal and platinum. Results are to be used along with other existing data to perform assessment of the ternary system under accord.

Phase equilibria in the CoO-SiO2 system

The emf method was employed to determine thermodynamic properties of cobalt orthosilicate, taking into account two different crystallographic forms of silica: amorphous and quartz. Results were then compared to available literature data and used along with other experimental information of the system to evaluate a thermodynamic description by the CALPHAD method.

Thermodynamics and phase diagram of the gallium-sodium system

A critical evaluation of the thermodynamic properties of liquid alloys was made. TheGibbs energies of formation of the solid compounds were derived from the original experimental data. Finally, calculations were carried out to match the thermodynamic description of the system to the known liquidus points.ZusammenfassungEs wurde eine kritische Auswertung der thermodynamischen Eigenschaften von flüssigen Legierungen durchgeführt. Von den experimentellen Daten wurden dieGibbsschen Bildungsenergien der festen Verbindungen abgeleitet. Letztlich wurden Berechnungen zur Anpassung der thermodynamischen Beschreibung des Systems mit bekannten Liquidus-Punkten durchgeführt.

Equilibrium diagram and thermodynamic properties of cadmium — antimony binary alloys. Critical assessment

Abstract Thermodynamic and phase diagram data were critically evaluated and and then optimized by Lukas method. Two alternative models :associates and Redlich-Kister polynomials were applied for the liquid and line compound was assumed in both cases. Calculated thermodynamic properties and phase boundaries were compared with the appropriate experimenta data and R-K description was accepted as that best suited for this system.