Identification of titanium oxide phases equilibrated with liquid Fe-Ti alloy based on EBSD analysis

Abstract

There are huge quantities of uncertainties on the Ti deoxdiation equilibrium constants and their interaction parameters in the literatures including the recommended values by the Japan Society for the Promotion of Science (JSPS). The main reason of such uncertainties among the previous works is due to the insufficient information of titanium oxide phase in equilibrium with liquid Fe-Ti alloy. The measurement of the equilibrium phase changes of titanium oxides with various Ti contents in molten Fe-Ti alloy has been carried out in the present study. Molten Fe-Ti alloys with various Ti contents have been equilibrated with 'Ti3O5' crucibles at 1 873 K. The kinds of Ti oxide at the interface of 'Ti3O5' crucible contacted with molten Fe-Ti alloys have been identified as the equilibrium titanium oxides with the electron backscatter diffraction (EBSD) pattern analysis technique. After the 'Ti3O5' crucible reacted with molten Fe-Ti alloys adequately and both of them were quenched. The present result on the stable region of equilibrium titanium oxides with Ti contents in Fe-Ti alloy was in good agreement with the thermodynamically calculated results based on the free energies of titanium oxides formation and the activity of Ti in Fe-Ti alloy. copy; 2006 ISIJ.