Phase equilibrium of the Fe2O3-TiO2 system

This study focused on the high-temperature phase equilibrium of the Fe2O3-TiO2 system by employing the classic phase equilibration and quenching method, X-ray diffraction, electron-probe microanalysis, and thermal analysis experiments. The solubility of the hematite, pseudobrookite, and rutile phases as the equilibrium temperature rose from 1100 °C to 1450 °C was determined. Besides, the solubility of TiO2 in the spinel phase at 1450 °C was verified by experiments. A comprehensive comparison with the phase diagram optimized by Panda indicates that the solubility of solid solutions involved in the Fe2O3-TiO2 system should be larger than the predicted one. Additionally, the ordered rutile phase was transformed into the high-temperature rutile-derived crystallographic shear structure at 1400 °C with Fe2O3 higher than 15 mol%. Furthermore, the eutectic reaction of liquid → pseudobrookite + rutile occurred at 1512 °C. The liquidus was determined to be 1512 °C and 1535 °C at 30 and 75 mol% of TiO2, respectively. These measured phase equilibrium data are expected to provide reliable input for future thermodynamic reassessments of the Fe2O3-TiO2 system within the CALPHAD framework.