Phase evolution during mechanochemical coreduction of V2O5 and TiO2 with A

Abstract

The direct preparation of V-Ti solid solution alloy by coreduction of V2O5 and TiO2 with Al in an attritor mill was investigated. The reduction of V2O5 with Al is highly exothermic, whereas reduction of TiO2 with Al is not sufficiently exothermic for a self-sustaining reaction. A range of compositions of a mixture of V2O5 and TiO2 can be so chosen as to make the overall reduction of V2O5 and TiO2 with Al sufficiently exothermic for a self-sustaining reaction. Initial studies were done to identify the reaction products obtained by reducing V2O5 with Al. The reaction yielded the intermetallic phase (Al3V), V, and Al2O3. SEM images indicated melting and solidification of the phases, leading to agglomeration. Further experiments involved mixing appropriate amounts of TiO2 with V2O5 and reducing the mixture with Al. XRD data for products showed the presence of V, V5Al8, and Al2O3. X-Ray Florescence (XRF) analysis and energy dispersive analyzer (EDAX) of SEM sample images indicated the formation of V-Ti solid solution. Microstructure of the milled charges taken out prior to reaction initiation indicated morphology change in Al powder and agglomeration/segregation of reactants. As a result, the reaction of V2O5 with the excess Al at certain regions also promoted the formation of vanadium aluminide.