Thermodynamic properties of liquid Al-Ge-Sn alloys: Part I. Calorimetric study (original) (raw)
Enthalpies of mixing of liquid Al–Fe–Ge alloys
Zeitschrift für Metallkunde, 2003
The partial and integral enthalpies of mixing of Al-Fe-Ge melts have been measured by high-temperature calorimetry at 1740 ± 5 K. The integral enthalpies of mixing at 1173 K, are about 4 to 6 kJ mol-1 less negative than determined by electromotive force measurement [9]. The integral enthalpies of mixing have been also estimated on the basis of the Bonnier geometric model. The calculated values show a reasonable agreement with experimental data for x Ge > 0.3. A difference between experimental and estimated integral enthalpies of mixing (up to 2.5 kJ mol-1) is observed for ternary alloys with low germanium content.
Calorimetric study of enthalpies of mixing in liquid (aluminium–gallium–yttrium) alloys
The Journal of Chemical …, 2006
The partial yttrium ðD mix H Y Þ and the integral (D mix H) enthalpies of mixing of liquid ternary Al-Ga-Y alloys have been determined by high-temperature mixing calorimetry at T = 1750 K. The measurements have been performed along five sections with constant ratios of Al and Ga in a range of 0.0 < x Y < 0.64. The D mix H has been estimated in the ternary system using asymmetric geometric models and the Toop model has been chosen as the most adequate one. The deviation between experimental and that predicted by the geometric model values of D mix H was found to be 1.54%, so ternary interaction is negligibly small at the experimental temperature. The possible contribution of binary intermetallide compounds into the thermodynamics of the liquid Al-Ga-Y alloys is discussed. (D.S. Kanibolotsky), lisnyak@chem.univ.kiev.ua (V.V. Lisnyak).
Thermodynamics of liquid aluminium–copper–germanium alloys
The Journal of Chemical Thermodynamics, 2003
Partial for aluminium and integral enthalpies of mixing of liquid Al-Cu-Ge alloys have been measured by high-temperature isoperibolic calorimetry at T ¼ ð1380 AE 5Þ K. Thermodynamic activities, partial for aluminium and integral Gibbs free energies of mixing have been determined by the electromotive force method (emf) over the range 1050 6 T =K 6 1250. Integral excess entropies of mixing have been calculated from calorimetric enthalpies and emf measured Gibbs free energies of mixing. The integral enthalpies of mixing and the integral excess Gibbs free energies of mixing have been also evaluated based on the literature data for boundaries using the Bonnier geometric model. Differences between experimental and calculated thermodynamic functions of mixing are positive. These facts as well as negative excess integral entropies of mixing reveal information about microsegregation in the melt. Therefore, the existence of ternary eutectic has been forecasted for Al-Cu-Ge phase diagram.
Enthalpies of mixing of liquid ternary Co–Li–Sn alloys
Monatshefte für Chemie - Chemical Monthly, 2014
The partial and integral molar enthalpies of mixing of liquid Co-Li-Sn alloys were determined using drop calorimetry. The investigations were performed along six sections by the addition of lithium to mixtures with the compositions x Co /x Sn & 2:98, x Co /x Sn & 1:9, and x Co /x Sn & 3:17 as well as by the addition of cobalt to mixtures with the compositions x Li /x Sn & 3:17, x Li /x Sn & 1:2, and x Li /x Sn & 1:1 at a temperature of 1,173 K. The Co-Li-Sn system shows exothermic behavior of the integral molar enthalpy of mixing in the investigated concentration range. The integral molar enthalpy of mixing of liquid Co-Li system was calculated by Miedema's model to fit our measured ternary data using an extended Redlich-Kister-Muggianu model for substitutional solutions.
Calorimetric investigation of liquid Al–Ga–Gd alloys
Thermochimica Acta, 2004
Partial for gadolinium and integral enthalpies of mixing were determined for liquid Al-Ga-Gd alloys using a high-temperature isoperibolic calorimeter at 1760 ± 5 K. The experiments were performed along five sections with constant concentration ratios of Al and Ga in a range of 0.0 ≤ x Gd ≤ 0.6. The resulted integral enthalpies of mixing were fitted by polynomial concentration dependences. The deviation between experimental and predicted by geometric model values of integral enthalpy of mixing was found to be 5.25%, so ternary interaction is negligibly small at the experimental temperature. It has been determined that ternary alloys thermodynamics is preferentially defined by influence of congruently melting binary GaAl 2 and GdGa 2 intermetallides.
Thermodynamic Properties of Liquid Ag-Bi-Sn Alloys
Journal of Electronic Materials, 2007
As a promising lead-free solder, the thermodynamic properties of the liquid ternary Ag-Bi-Sn system were investigated. Using an appropriate galvanic cell, the partial free energies of Sn in liquid Ag-Bi-Sn alloys were determined as a function of concentration and temperature. Thermodynamic properties were obtained for 27 alloys. Their composition was situated on three cross sections with the constant ratios of Ag:Bi = 2:1, 1:1, and 1:2. The integral Gibbs free energy and the integral enthalpy for the ternary system at 900 K were calculated by Gibbs-Duhem integration.
Enthalpies of mixing of the liquid phase in the ternary system Ag–Au–Bi
Journal of Alloys and Compounds, 2005
The enthalpies of mixing of the liquid phase of the Ag-Au-Bi ternary alloys along the sections Ag x Bi 1−x-Au (x = 0.11, 0.10 and 0.24) and Au x Bi 1−x-Ag (x = 0.11 and 0.27) have been determined at 673 and 773 K. We used a SETARAM devised heat flow calorimeter of Tian-Calvet type. The values obtained are almost compatible with estimations from Scientific Group of Thermodata Europe (SGTE) binary database without adding ternary thermodynamic excess parameters. However, slight discrepancies are observed. The result of this study is useful tools for the Ag-Au-Bi ternary system thermodynamic computer optimization in process by the authors.
Thermodynamic properties of liquid Al-Si and Al-Cu alloys
Journal of Thermal Analysis and Calorimetry, 2002
The partial and integral enthalpies of mixing in liquid Al-Si and Al-Cu alloys were determined by high-temperature isoperibolic calorimetry at 1750±5 and 1590±5, respectively. The thermodynamic properties of Al-Si melts were also studied by electromotive force method in temperature range 950-1270 K. The partial and integral excess Gibbs free energies of mixing in liquid Al-Si and Al-Cu alloys were calculated from literature data on thermodynamic activity of aluminium. The comparison of our experimental results with literature data has been performed.
The thermodynamic properties of the liquid Ag–Ga alloys were determined using e.m.f. and calorimetric methods. In the e.m.f. method, solid oxide galvanic cells were used with zirconia electrolyte. The cells of the type W; Ag x Ga ð1ÀxÞ ; Ga 2 O 3 ==ZrO 2 þ ðY 2 O 3 Þ==FeO; Fe; W were used in the temperature range from 1098 K to 1273 K, and in the range of mole fraction from x Ga = 0.1 to x Ga = 1.0. At first, the Gibbs free energy of formation of pure solid gallium oxide, Ga 2 O 3 , from pure elements was derived. Using values of the measured e.m.f. for the cell with x Ga = 1.0, the following temperature dependence was obtained: D f G m;Ga 2 O 3 ðAE4 kJ Á mol À1 JÞ ¼ À1061:7235 þ 0:2899T=K: Next, the activity of the gallium was derived as a function of the alloy composition from the values of the measured e.m.f. Activities of silver were calculated using the Gibbs–Duhem equation. The drop calorimetric measurements were carried out at two temperatures, viz. 923 K and 1123 K, using a Setaram MHTC calorimeter. Integral enthalpies of mixing of liquid binary alloys were determined at those temperatures. Finally, thermodynamic properties of the liquid alloys were described with the Redlich–Kister equation using ThermoCalc software.