Formation of titanium and niobium aluminides induced by hydrogen in a hydride cycle

The results of our study of formation of aluminides by the hydride cycle (HC) method in Ti–Al and Ti–Al–Nb systems and of their hydrides under the conditions of self-propagating high-temperature synthesis are presented. The HC method was developed at the High-Temperature Synthesis Laboratory of the Nalbandyan Institute of Chemical Physics, Armenian Academy of Sciences. The effect of various parameters: the ratio of titanium and niobium hydrides and aluminum powders in the reaction mixture, hydride powder grain size (micro and nano size), compacting pressure during compaction of hydrides, and conditions of dehydrogenation and sintering (heating temperature and rate) on the characteristics of the obtained aluminides: crystal structure, density, etc. was studied. As a result, single-phase aluminides α₂-Ti₃Al, Ti₂Al, γ-TiAl, TiAl₃, Ti_0.33Al_0.34Nb_0.33, Ti_0.5Al_0.23Nb_0.27, Ti_0.52Al_0.15Nb_0.33, TiAl₆Nb, etc., and hydrides were synthesized. The HC method has significant advantages over conventional procedures: low temperature (1000–1100°C) and processing time (30–60 min), one-stage formation of single-phase aluminides, etc.