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Fabrication of FeSi-Al₂O₃ composites with a molar ratio of FeSi/Al₂O₃ ranging from 1.2 to 4.5 was conducted by the self-propagating high-temperature synthesis (SHS) method. The synthesis reaction involved metallothermic reduction of Fe₂O₃ and SiO₂ by Al and the chemical interaction of Fe and Si. Two combustion systems were examined: one contained thermite reagents of 0.6Fe₂O₃ + 0.6SiO₂ + 2Al, and the other had Fe₂O₃ + 2Al to mix with different amounts of Fe and Si powders. A thermodynamic analysis indicated that metallothermic reduction of oxide precursors was sufficiently exothermic to sustain the combustion reaction in a self-propagating mode. The SHS reaction carrying out co-reduction of Fe₂O₃ and SiO₂ was less exothermic, and was applied to synthesize products with FeSi/Al₂O₃ = 1.2–2.5, while the reaction reducing only Fe₂O₃ was more energetic and was adopted for the composites with FeSi/Al₂O₃ = 2.5–4.5. Moreover, the former had a larger activation energy, i.e., <i>E_a</i> = 215.3 kJ/mol, than the latter, i.e., <i>E_a</i> = 180.4 kJ/mol. For both reaction systems, the combustion wave velocity and temperature decreased with increasing FeSi content. Formation of FeSi-Al₂O₃ in situ composites with different amounts of FeSi was achieved. Additionally, a trivial amount of aluminum silicate was detected in the products of high FeSi contents due to dissolution of Si into Al₂O₃ during the SHS process.