Abstract
The partial and integral enthalpies of mixing of liquid binary alloys in the systems Ag-Sn, Cu-Sn and Ni-Sn were determined at different temperatures from 500 to 1500 degrees C using drop calorimetry techniques. Generally, our measured values fit well to most of the hitherto reported results. The data were fitted using a Redlich-Kister polynomial and the binary interaction parameters were evaluated. For all three systems the enthalpy curves at various temperatures are discussed focusing on the association theory. C-ass, C-A1,C-B1, C-A1,C-AiBj, C-B1,C-AiBj, the interaction parameters and K-AiBj were determined. The general shape and supposed temperature dependence of the enthalpy of mixing in Ag-Sn and Cu-Sn could be confirmed. No significant temperature dependence could be found experimentally for Ni-Sn at temperatures above 1100 degrees C. Extrapolations into the metastable liquid regions based on the association theory, however, indicate a small drop of Delta H-Mix with temperature. A second series of measurements limited to low concentrations of Ag, Cu, or Ni, respectively in Sn has been performed in order to determine the partial enthalpies of mixing at infinite dilution at 500, 600, 700, and 800 degrees C. Temperature dependence could be observed for all three binary systems, most developed for Ni-Sn. (C) 2008 Elsevier B.V. All rights reserved.