Thermodynamics of the Oxygen Solutions in Chromium-Containing Melts of the Fe-Co System

Thermodynamic analysis of the oxygen solutions in chromium-containing melts of the Fe-Co system is carried out. The equilibrium constants for the interaction of chromium and oxygen, the activity coefficients at infinite dilution, and the interaction parameters in melts of various compositions are deter-mined. The dependences of the oxygen solubility in the melts on the cobalt and chromium contents are calculated. Chromium in iron-cobalt melts is characterized by a fairly high oxygen affinity, which substantially increases with the cobalt content in a melt. The introduction of chromium into a melt in manufacturing iron-cobalt alloys results in the final metal with a lower oxygen concentration. The solubility curves of oxygen in chromium-containing iron-cobalt melts pass through a minimum, whose position shifts toward low chro-mium contents as the cobalt content in a melt increases. Further chromium additives result in an increase in the oxygen concentration in a melt. The higher the cobalt content in the melt, the sharper the increase in the oxygen concentration after the minimum when chromium is added to the melt.