Thermodynamic properties of α Cu-ln alloys by the method of atomic absorption

Abstract

Atomic absorption spectroscopy was used to measure the vapor pressure of indium over seven binary alloys of the α Cu-ln system. Thermodynamic activity, partial molar enthalpy and partial molar entropy of indium were calculated from the vapor pressure and its tem-perature coefficient. The activity coefficient obtained has a large value for alloys of this type, even when referred to a solid reference state. The partial molar enthalpy values are lower than expected for a trivalent solute. The excess partial molar free energy, when plotted against atom fraction, shows a minimum at about 7 at. pct indium. The reason for the occurrence of a minimum in\(\overline {\Delta G} _{^{In} }^{XS} \) is not known.