Ti deoxidation equilibrium in molten Fe-Cr and Fe-Cr-Ni alloys at temperatures between 1823 K and 1923 K

Abstract

Titanium deoxidation equilibria between Ti and O in molten Fe-Cr and Fe-Cr-Ni alloys were investigated at temperatures of 1 823 to 1 923 K. Titanium oxides equilibrated with molten Fe-Cr and Fe-Cr-Ni alloys have been determined by EBSD (Electron Backscatter Diffraction) pattern analysis using FE-SEM (Field Emission Scanning Electron Microscope). Deoxidation product changes from Ti 2O3 to Ti3O5 with decrease of Ti content in Fe-Cr and Fe-Cr-Ni alloys. Binary interaction parameters of Redlich-Kister type polynomial between Cr and O was assessed by using the previous experimental result in the Fe-Cr-O system. Experimental result of titanium deoxidation in molten Fe-Cr alloy has been numerically analyzed by the excess Gibbs free energy change of mixing Fe-Cr-Ti-O system with Redlich-Kister type polynomial. Validity of evaluated parameters between Cr-O (Ω2 Cr-o) and Cr-Ti (ΩCr-Ti) was confirmed by comparison with experimental result for Fe-Cr-Ni alloy. Binary interaction parameters of Redlich-Kister type polynomial in present work were evaluated as follows, 0ΩCr-O=-52 870-24.10T J/mol (Xo<0. 0015, 1 823≤T≤1 923 K) 1ΩCr-o=-498 200+234.7T J/mol (Xo<0.0015, 1 823≤T≤1 923K) 0Ω Cr-Ti=365 700-206.3T J/mol (XTi<0.003, 1 823≤T≤1923 K) 1ΩCr-Ti=432 900-208.8T J/mol (XTi<0.003, 1 823≤T≤1 923 K) © 2009 ISIJ.