Direct reduction of upgraded titania slag by magnesium for making low-oxygen containing titanium alloy hydride powder

Abstract Upgraded titania slag (UGS) is a titanium-rich material with over 90 wt% titanium dioxide and some minor elements such as Fe, Al, Cr, and Si, which is mainly used for preparing TiO2 and TiCl4. In this study, UGS was directly reduced with magnesium powder in a hydrogen atmosphere. Titanium alloy hydride powder with the oxygen content of 0.032 wt% was obtained. The minor elements of Fe, Si, Al, and Cr from the UGS were kept in the final powder with the main phase of TiH1.924(δ), and minor intermetallic phases of HFe2Ti, Ti5Si3H0.9 and Cr1.8TiH5.3. EDS elemental mapping results indicated that HFe2Ti and Ti5Si3H0.9 intermetallics formed bright phase islands in the matrix. The reduction mechanism and the reaction sequence were discussed based on the thermodynamic modelling with the assistance of HSC chemistry software. The possibility of hydrogen reduction of titanium oxides was discussed as well.