Activities of phosphorus in copper-cobalt liquid alloys saturated with solid copper-cobalt solid solutions at 1573 K

In order to elucidate the thermodynamic properties of phosphorous in liquid {Cu-Co-P} alloys, 2-phase coexistence of {Cu-Co-P} liquid alloys and Cu-Co-P solid solutions were brought into equilibrium with a mixture of Al2O3 and AlPO4 at 1573 K. The equilibrium reaction underlying the experiments can be expressed by the formula Al2O3 + 2P(%, in Cu) + (5/2)(O-2) = 2(AlPO4). The equilibrium oxygen partial pressures were determined via electrochemical measurements involving stabilized zirconia as a solid electrolyte and a mixture of Mo and MoO2 as a reference electrode. The activities of phosphorus were then determined along liquidus line of the ternary system of Cu-Co-P.