Activities of Oxygen in Liquid Cu–In and Cu–Sn Alloys determined by a Modified Coulometric Titration Method

Abstract

The activity coefficients of oxygen, γo, in liquid Cu–In and Cu–Sn alloys at 1373 K have been measured over the entire composition range utilizing a modified coulometric titration method with the electrochemical cell: O in liquid Cu–In or Cu–Sn alloys/ZrO₂(+CaO)/Air, Pt. The measured In γo values, plotted in terms of indium or tin mole fraction, lie on a S-shaped curve, as predicted by Jacob and Alcock’s quasi-chemical equation. The present results for Cu–In alloys were significantly different from published values, while the results for Cu–Sn alloys were in reasonable agreement with reliable published values. The interaction parameters of indium and tin on oxygen in liquid copper were evaluated from the present data for the dilute alloys to be ε₀^(In)=−8.9 and ε₀^(Sn)=−2.8 at 1373 K, respectively.