Aluminum Deoxidation Equilibrium in Molten Fe–Co Alloys

Abstract

Aluminum deoxidation equilibrium of molten Fe–Co alloy was experimentally measured using a chemical equilibrium method and numerically assessed using a sub-regular solution model based on Darken’s quadratic formalism and a Redlich-Kister type polynomial at 1873 K. It was found that the degree of oxygen content reduction by Al-deoxidation decreased with increasing cobalt concentration in the alloy, peaking at around 40 to 60 mass% Co, and then improved with further increase in cobalt concentration. The following binary interaction parameters between cobalt and aluminum were derived in this study:

0ΩCo-Al = -387360 [J/mol], 1ΩCo-Al = 309420 [J/mol]

It was also found that the above binary interaction parameters can accurately determine Al-deoxidation equilibrium of pure liquid cobalt. Finally, the critical point at which Al2O3 and CoO·Al2O3 coexist throughout the whole composition range of the alloy was also estimated from the experimental results in this study.