Solubility of oxygen in titanium-containing iron-nickel melts

The solubility of oxygen in titanium-containing iron-nickel melts is studied experimentally for the example of Fe-40% Ni alloy at 1873 K. The experiments yield values for the equilibrium constant of the reaction of titanium and oxygen dissolved in Fe-40% Ni melt (logK(1)(Fe - 40% Ni) = −15.17), the Gibbs energy of that reaction (ΔG(1)(Fe-40%Ni) °=543 360 J/mol), and the interaction parameters for those solutions (eTi(Fe-40%Ni) O=-1.420; eO(Fe-40%Ni) Ti=-0.472; eTi(Fe-40%Ni) Ti=0.116). For a broad range of alloy compositions in the Fe-Ni system, the equilibrium constant of the reaction of titanium and oxygen dissolved in the melt, the Gibbs energy of that reaction, and the interaction parameters for those solutions are calculated at 1873 K. The solubility of oxygen in titanium-containing iron-nickel melts is determined at 1873 K. The reducing properties of titanium fall with increase in the Ni content to 40% and then increase sharply with further increase in the melt’s Ni content. This may be explained in that increase in the Ni content is associated, on the one hand, with significant decrease in the bond strength of oxygen atoms in the melt (γO(Fe) °=0.0103; γO(Ni) °=0.0337) and, on the other, with considerable increase in the bond strength of titanium atoms (γTi(s)(Fe) °=0.0083; γTi(s)(Ni) °=0.000083). The solubility curves of oxygen in iron-nickel melts pass through a minimum. As the Ni content increases, the minimum is shifted to lower Ti content. © 2014, Allerton Press, Inc.