Thermodynamic properties of liquid Al-Ge-Sn alloys: Part I. Calorimetric study (original) (raw)
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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.
Enthalpies of mixing estimation in the liquid X-In-Sn-Zn (X=Ag, Au) alloys
2015
Results of thermodynamic predicting methods applied to the quaternary metallic X-In-Sn-Zn (X = Ag and Au) systems based on their sub-binary systems are presented in this work. The general solution model of Chou has been used to estimate the integral enthalpies of mixing of the investigated systems. The other traditional models such as Muggianu and Toop are also included in estimations for comparison. The estimations were carried out at 773 K along five starting ternary compositions InxSnyZnz with additions of Ag or Au. In the Ag-In-Sn-Zn system, the estimated enthalpies of mixing using Chou’s model are close to those predicted by a symmetric Muggianu’s model, while for the Au-In-Sn-Zn, the values obtained by Chou’s model are in good agreement with those of an asymmetric Toop’s model.
Heat of Mixing and Activities in Liquid Al-Sn Alloys
Zeitschrift für Naturforschung A, 1979
The microscopic electron theory based on the pseudopotential formalism has been applied to the calculation of the heats of mixing and of activities in liquid Al-Sn alloys. The calculated values for both quantities were found to be in reasonable agreement with the experimental data.
Calorimetric study of enthalpies of mixing in liquid gallium-germanium-yttrium alloys
Thermochimica Acta, 2005
The yttrium partial enthalpies of mixing ( mixHY ) and the integral enthalpies of mixing ( mix H) of liquid Ga-Ge-Y alloys have been determined by high-temperature mixing calorimetry for five sections with constant ratios of Ga and Ge at 1760 K. Plots of concentration dependence of mixHY /(1 − x Y ) 2 show sharp inflections, which correspond to transition of the liquid alloys into heterogeneous state and can be used for determination of liquidus surface. Furthermore, the mix H has been estimated in the ternary system using seven geometric models and the Bonnier model has been chosen as the most adequate one. The differences between the experimental and model integral enthalpies of mixing have been described by polynomial concentration dependence. The possible contribution of binary and ternary intermetallide compounds into the thermodynamics of the liquid Ga-Ge-Y alloys has been considered.
The Journal of Chemical Thermodynamics, 2006
ABSTRACT Liquid alloys of (gadolinium-germanium-manganese) have been studied by a high-temperature mixing calorimetry at (T = 1830) K. The measurements have been performed along five sections with x(Ge):x(Mn) = 0.25:0.75, 0.4:0.6, 0.5:0.5, 0.7:0.3, and 0.8:0.2 for 0.0 < X-Gd < 0.55. The integral enthalpy of mixing (Delta H-mix) has been calculated from the experimental Delta(mix)(H) over bar (Gd) by Darken's equation. The values of Delta H-mix have been also estimated using nine geometric models and the results of Muggianu model implementation provide the best agreement with the experimental data. Two interpolation methods have been used for describing the integral enthalpy of mixing in the ternary liquid alloys. The Delta H-mix values estimated by the interpolation methods agree as well with each other as with the Muggianu model prediction. The differences between the Delta H-mix values determined by experiment and from the model are small and vary from (-4.2 up to 3.5) kJ . mol(-1), which is evidence for a negligibly small ternary interaction in liquid (Gd-Ge-Mn) alloys. Extreme Delta H-mix values are observed in the boundary (Gd-Ge) system. Consequently, the interaction between Ge and Gd atoms make a major contribution to the thermodynamics of liquid (Gd-Ge-Mn) alloys.
Enthalpy of mixing in liquid Al–Fe–Si alloys at 1750K
Thermochimica Acta, 2003
The partial for aluminium and integral enthalpies of mixing in liquid Al-Fe-Si alloys have been measured by high-temperature isoperibolic calorimetry at 1750 ± 5 K. The study has been performed along five sections with constant concentration ratios of Si and Fe. The integral enthalpies of mixing were simulated according Bonnier geometry. The differences between experimental and simulated data possess negative values within the experimental errors range, which may testify that ternary interaction is negligibly small at the experimental temperature.