Temperature dependence of Ti deoxidation equilibria of liquid iron in coexistence with Ti3O5' and Ti2O3

Abstract

The equilibrium relation between Ti and O in liquid Fe has been measured only at 1 873 K on the condition of various kinds of titanium oxides saturation in our previous paper. The present work deals with the equilibrium between Ti and O in liquid Fe saturated with 'Ti3O5' and Ti 2O3 at 1 823 K and 1 923 K for full understanding temperature dependence. Also, equilibrium phase changes of titanium oxides with various Ti contents in molten Fe have been identified as the equilibrium titanium oxides with electron backscatter diffraction (EBSD) pattern analysis technique. The present results have been thermodynamically evaluated combining with previous results on the various thermodynamic values as a function of temperature. The equilibrium constants and the interaction parameters of Wagner's formalism were given as a function of temperature in the present work as follows. Ti2O3(S) = 2Ti+3O. (-10.61, 0.28 <4.89, at 1823K logKTi2O3=-42 940/T + 12.94, (1823K <6.22, at 1873K (-9.39, 0.52 <2.79, at 1923K eOTi = -701/T+0.0344, (1 823K <0.28, at 1823K logK'Ti3O5' = -68280/T +19.95, (1823K <0.40, at 1873K -15.56, 0.0045 <0.52, at 1923K eOTi = -701/T+0.0344, (1 823 K <7<1 923K) The self-interaction parameter of Ti in liquid Fe was obtained as a function of temperature. eTiTi = 212/T-0.0640, (1 823 K <7<1 923 K) The estimated results based on Wagner's formalism as well as Darken's quadratic formalism with Redlich-Kister type polynomials agreed well with the experimental results at 1 823 to 1 923 K. © 2008 ISIJ.