Thermodynamic Relation between Aluminum and Titanium in Liquid Iron

Abstract

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 1843–1973 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 = 1939/T−1.009, e_Al^Ti = 1092/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 1873 K.