A Thermodynamic Study of Solid Iron-Gold and Cobalt-Gold Alloys by the Use of Solid Oxide Electrolytes

AbstractThe thermodynamic properties of iron-gold and cobalt-gold alloys have been measured between 750 and 1000° C by an e.m.f. method with ThO2–YO1.5 electrolytes. Results are given for activities, entropies, and heats of mixing across the complete range of composition and the phase diagrams published in Hansen's compilation (M. Hansen and K. Anderko, “Constitution of Binary Alloys”. 1958: New York and London (McGraw-Hill))are shown to be consistent with the thermodynamic results now obtained. It is concluded that the heat-of-mixing term is the dominant factor in defining the phase fields of the diagrams and a tentative model is proposed.