Special features of Al$_9$Mn$_3$Si $\gamma$-phase formation during high-temperature synthesis in Al–Mn–Si : combustion, structurization, and phase formation

This paper is devoted to the preparation of Al–Mn–Si-based compounds with different Si contents (0, 5, 10, and 15 at.%) using self-propagating high-temperature synthesis (SHS). This method is used for the first time to obtain the Al$_9$Mn$_3$Si $\gamma$-phase with a hexagonal crystal lattice (P6$_3$/mmc space group) as part of a synthesized alloy with a content of 15 at.% of Si in the initial mixture. The X-ray diffraction analysis of the synthesized alloys from mixtures with a silicon content of 5–10 at.% also shows the presence of $\gamma_2$-Al$_8$Mn$_5$ (trigonal, R3m space group) and MnSi (cubic, Pm-3m space group) phases. The phase formation of intermediate compounds at silicon content in a mixture below 15 at.% may be associated with combustion temperature, which is insufficient for complete interaction of the system components. Synthesized alloys are characterized by a porous structure with pore size up to 20 $\mu$m and a grain size in the pore space of 10–90 $\mu$m.