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

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 Nb$_2$O$_5$ with Al, Si, Hf, and Ti. It has been found that in the combustion wave, Hf actively participates in reducing Nb$_2$O$_5$, which complicates its introduction into the composite material, and also leads to an excess of Al in the alloy. In the present study, we have investigated the possibility of replacing Hf in the starting mixture by less active HfAl$_3$ and have also determined the effect of dispersion of HfAl$_3$ on the Hf content in the composite material.