CALCIOTHERMIC PRODUCTION OF NIOBIUM ALUMINIDE (NbAl 3)

A process based on calciothermic reduction of Nb2O5 in the presence of aluminium has been developed for the production of NbAl 3 (Niobium aluminide). In this scheme, the charge constituents - Nb2O5 and aluminium in the powder form and calcium granules are thoroughly mixed and reacted at temperatures above 1173 K in argon atmosphere. The reduced mass is leached with acetic acid and water to recover the alloy product. The alloy was then analysed chemically for composition and by XRD for identification of the phases present. After a series of experiments, it has been established that single phase alloy of NbAl 3 could be produced under conditions of stoichiometric amounts of the oxide and aluminium with 20% excess of calcium reductant and reduction at a temperature of 1273 K for 8 h duration.