Joint Metallothermic Reduction of Titanium and Rare Refractory Metals of Group V

The features of phase formation during the joint aluminothermic reduction of titanium, niobium, tantalum, and vanadium from their oxides are studied using thermodynamic modeling and differential thermal (DTA) and X-ray diffraction phase analysis. Using computer thermodynamic modeling made it possible to predict the optimal temperature conditions in the metallothermic process, the composition and ratio of the reagents in the charge, the behavior of the elements, and the sequence of the phase formation. To identify the kinetic and thermochemical components of the process, thermodynamic calculations are supplemented by differential thermal studies using combined scanning calorimetry. An analysis of the theoretical and experimental data shows that the interaction of aluminum with titanium dioxide proceeds through the stage of formation of titanium monoxide and results in the formation of Ti x Al y intermetallic compounds of various compositions (TiAl 3 , TiAl, and Ti 2 Al) depending on the Al to TiO 2 ratio in the batch. When titanium dioxide is partially replaced by niobium, tantalum, and vanadium oxides, the metallothermic process under interactions in the Al–TiO 2 –Nb 2 O 5 , Al–TiO 2 –Ta 2 O 5 , and Al–TiO 2 –V 2 O 5 systems is of the similar character; enters the active phase after the formation of liquid aluminum; is accompanied by exothermic effects; and is characterized by the priority formation of titanium aluminides and binary and ternary intermetallic aluminum compounds with rare refractory metals of group V such as AlNb 3 , Al 3 Nb, Al 3 Ta, Al 3 (Ti 1 – х ,Ta х ), Al 3 (Ti,Ta), and Al 3 (Ti 0.8 V 0.2 ). The joint conversion of titanium dioxide and rare refractory metal pentoxides during the reduction process is affected through sequential and parallel stages of the formation of simple and complex element oxides with low oxidation states.