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The oxygen solutions in the titanium-containing Fe-Ni melts have been thermodynamically analyzed. When the nickel content rises to 40 %, the deoxidation ability of titanium decreases but then it sharply rises with increasing nickel concentration in melt. This can be explained by the fact that although the bond strength of titanium in nickel is considerably stronger in comparison with iron (g°T i(s)(Fe) ϭ0.0083; g°T i(s)(Ni) ϭ0.00019), but the bond strength of oxygen in nickel is appreciably weaker that in iron (g°O (Fe) ϭ0.0105; g°O (Ni) ϭ0.357). The oxygen solubility curves pass through a minimum whose position shifts to the higher titanium concentrations with an increase in the nickel content from 0.564 % Ti for pure iron to 0.633 % Ti for pure nickel. The further addition of titanium causes an increase in the oxygen content in melt. Equilibrium points of oxide phases TiO 2 , Ti 3 O 5 and Ti 2 O 3 for different alloy compositions at 1 873 K were determined. The published results devoted to the oxide phases in iron and nickel deoxidized with titanium are summarized. Deoxidation of Fe-40%Ni melts with titanium was experimentally studied. The experimental and calculated results are in good agreement. The deoxidation abilities of titanium, chromium, manganese, vanadium, silicon, carbon, and aluminum in different Fe-Ni alloys are compared.

Thermodynamic analysis of oxygen solutions in iron-nickel melts with chromium has been carried out. Since the bond strength of oxygen with such a melt becomes weaker with an increase in the nickel concentration (g°O (Fe) ϭ0.0105; g°O (Ni) ϭ0.357), the deoxidation power of the chromium in liquid nickel is higher than that in iron melt.The deoxidation power of chromium remains almost constant when the nickel concentration in melt increases to 20 % but it rises sharply with a further increase in its content. Oxygen solubility curves pass through a minimum, which shifts to lower chromium contents in a range of from Ϫ7% Cr (pure iron) to Ϫ1.7 % Cr (pure nickel) when the nickel concentration rises. Minimum oxygen concentrations in nickel are lower almost by an order of magnitude as compared to iron. Subsequent chromium additions cause an increase in the oxygen concentration in melt; in this case, the higher the nickel content, the sharper the rise in the oxygen concentration after the minimum when chromium is added. Deoxidation of iron-nickel melts with chromium was experimentally studied for the Fe-20%Ni, Fe-40%Ni and Fe-60%Ni alloys. Experimental and calculated results are in good agreement.

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