Structural scheme of chemical transformation in a $\mathrm{Fe}_2\mathrm{O}_3+\mathrm{Al}+\mathrm{AlN}$ wave combustion in nitrogen

The stages of chemical transformation in the combustion wave of an exothermic $\mathrm{Fe}_2\mathrm{O}_3/\mathrm{Al}/\mathrm{AlN}$ mixture in nitrogen atmosphere is studied using an original method for terminating a combustion front. It is revealed that, in a stoichiometric $\mathrm{Fe}_2\mathrm{O}_3/6\mathrm{Al}$ mixture diluted with $35\%$ (wt.) $\mathrm{AlN}$, the combustion front stops following the combustion of a $30-40$-mm mixture column. The zones of a stopped combustion wave are investigated by the local analysis methods. It is shown that the alumothermal reduction of iron (III) oxide to iron aluminide proceeds in stages via the formation of a $(\mathrm{FeAl})_x\mathrm{O}_y$ double oxide having varying chemical composition. The final synthesis products include aluminum oxynitride, iron aluminide, and unreacted aluminum nitride.