Production of Ti–W Alloys from Mixed Oxide Precursors via the FFC Cambridge Process

Ti – 10 wt % W alloys were produced via the electrochemical deoxidation of mixed Ti O 2 + W O 3 sintered precursors in a molten Ca Cl 2 electrolyte at 1173 K . Fully metallic samples were retrieved after 15 h of reduction. This reduction time was longer than that observed for metallization of ( Ti , Mo ) O 2 sintered precursors. This was believed to occur as a result of significant differences in the reduction pathway, despite tungsten and molybdenum possessing similar interactions with titanium. It was found that the reduction initiated with the rapid reduction of W O 3 to a fine W–Ti particulate. Ti O 2 then proceeded to reduce sequentially through the lower oxides, with concurrent formation of Ca ( Ti , W ) O 3 . Between 1 and 3 h of reduction the sample is believed to be composed of Ca ( Ti , W ) O 3 and TiO. A comproportionation reaction between these two phases is then observed, resulting in the formation of W–Ti and Ca Ti 2 O 4 . However homogenization between the product titanium and W–Ti does not take place until the titanium is sufficiently deoxidized; thus, β - Ti forms late in the reduction process. It is believed that the late formation of β - Ti in the reduction process, coupled with the lack of a conductive metal oxide network, accounts for the relatively slow reduction time.