Solubility of oxygen in carbon-bearing Fe-Ni melts

Abstract

Oxygen solutions in carbon-bearing Fe-Ni melts are analyzed thermodynamically. The equilibrium oxygen concentrations in Fe-Ni alloys in the presence of carbon have been determined for the first time over a wide composition range and a wide range of the partial pressures of carbon mono-and dioxides. As the carbon concentration increases, the oxygen concentration decreases in melts of all compositions. As the nickel content in the melt increases, the equilibrium oxygen concentration decreases at the same carbon concentration. The difference in the oxygen concentrations in iron and nickel at the same carbon concentration is almost two orders of magnitude, which can be explained by the substantial weakening of the bonding forces of oxygen in the melt and the less pronounced weakening of the bonding forces of carbon atoms with increasing nickel content. The oxygen solubility curves pass through a minimum, whose position changes with the nickel content from 2.443% C for pure iron to 2.842% C for pure nickel. The solubility of oxygen in a Fe-40% Ni melt is experimentally studied at various carbon contents. The experimental results agree well with the calculated data.