Thermodynamic relation between aluminum and titanium in liquid iron

Thermodynamic relation between aluminum and titanium in liquid iron was studied using the metal-nitride-gas equilibration technique. The effect of aluminum on the solubility product of TiN in liquid iron was measured under different nitrogen partial pressures in the temperature range of 1 843-1 973 K. The experimental results were thermodynamically analyzed using Wagner's interaction parameter formalism to determine the first-order interaction parameters of aluminum and titanium in liquid iron as follows. e(Ti)(Al)=1 939/T-1.009, e(Al)(Ti)= 1 092/T-0.568 Using thermodynamic data determined in present study, a stability diagram for Al2O3, Ti2O3 and Ti3O5 phases was constructed as a function of dissolved aluminum, titanium and oxygen contents in liquid iron. The result indicated that at equilibrium condition titanium oxides would not form on titanium addition in Al-killed liquid steels with soluble aluminum content of 0.02-0.05 mass% at 1 873 K.