Autowave chemical transformations of highly exothermic mixtures based on niobium oxide with aluminum

Abstract

Composite materials based on Nb with functional (Si, C, B) and alloying dopants (Hf, Ti, Al, etc.) are promising materials for aircraft engine applications. Our previous studies have shown that such composites can be synthesized in the autowave mode (combustion mode) using highly exothermic mixtures of Nb₂O₅ with Al, Si, Hf, and Ti. It has been found that in the combustion wave, Hf actively participates in the reduction of Nb₂O₅, which complicates its introduction into the composite material and leads to an excess of Al in the alloy. In the present study, we investigated the possibility of replacing Hf in the starting mixture by less active HfAl₃ and also determined the effect of the grain size of HfAl₃ on the Hf content in the composite material.