Activities of boron in the binary Fe-B, Co-B, and Cu-B melts

Abstract

Activities of boron in the binary Fe-B, Co-B, and Cu-B melts have been directly determined by the electromotive force (emf) measurement. Boron-saturated liquid Cu-B alloy was used as the reference electrode and a ternary 28 wt pct Al2O3-29 wt pct B2O3-43 wt pct CaO oxide melt was used as the electrolyte. Deviations of the boron activities from Raoult's law have been found largely negative for the Fe-B and Co-B systems but largely positive for the Cu-B system. Boron activities calculated from the literature data have not been in good agreement with the measured data. Activities of iron, cobalt, and copper have been calculated from the obtained boron activities by means of the Gibbs-Duhem equation. Some modifications to the liquidus curves on the Fe-B and Co-B phase diagrams have been presented.