Deoxidation equilibrium of vanadium in the iron-nickel melts

Abstract

Thermodynamic analysis of oxygen solutions in the Fe-Ni melts with vanadium has been carried out. The deoxidizing ability of vanadium decreases slightly with the nickel content up to 20% but it considerably rises with a further increase in its concentration. The oxygen solubility curves pass through a minimum, which shifts to the lower vanadium concentrations with a rise in the nickel content, i.e., from 2.32% for pure iron to 0.77% for pure nickel. The further vanadium addition causers an increase in the oxygen concentration in melt. For pure nickel or alloys with the nickel concentration higher than 60%, the deoxidizing ability of vanadium is lower in comparison with that of manganese and is close to the deoxidizing ability of chromium. This can be explained by the fact that although the bond strength of oxygen with nickel is appreciably weaker as compared to that with iron (γ°O(Fe)= 0.0105; γ°O(Ni)=0.357), but the vanadium bond strength with nickel is much stronger than that with iron (γ°V(Fe)=0.1; γ°V(Ni)=0.011). The deoxidation of iron-nickel melts with vanadium was experimentally studied by the example of the Fe-40%Ni alloy. © 2009 ISIJ.