Activity Determination of Cobalt in Cobalt–Gold Alloys

Abstract

Activities of cobalt in cobalt–gold liquid alloys from 1250 to 1335 °C were determined by equilibrating the alloy with pure solid CoO under a CO/CO2 gas mixture of known oxygen partial pressure. The cobalt activities were calculated from the cobalt content of the alloys after equilibration. The activities of gold were calculated by Gibbs–Duhem integration. In the present study, both activities showed positive deviations from ideality. In the terminal region, the cobalt–gold system was found to behave as a regular solution. The temperature effect on the activities was found to be negligible.