Design and reaction characteristics of heterogeneous ternary Al–Mg–Si alloy fuels

Highly active Al-based alloy fuels are the most popular alloy fuel for energetic materials. However, the presence of highly active metals (Li, Mg, etc.) and their alloy compounds affects their combustion stability. In this study, two kinds of Al–Mg–Si ternary alloy fuels with silicon content of 2.5% and 5% were prepared by centrifugal physicochemical method to enhance their thermal stability and combustion stability. The microstructure, thermal stability, and combustion stability of the alloy fuels were investigated using SEM, FIB micro-nano processing, TG-DSC, and laser ignition, and the combustion mechanism was elucidated. The results showed that the Al–Mg–Si alloy fuels had a relatively smooth spherical surface that was composed of αAl, Mg₂Si, and a small amount of Al₃Mg_2, and the particle size is 27.9–32.6 μm. Compared with Al–Mg alloy fuel, the composite oxide layer of ternary alloy fuel is thinner. Compared with the Al–Mg alloy fuels, the Al–Mg–Si alloy fuels exhibited lower oxidation temperatures, higher oxidation peak temperatures, and better thermal stability. Ignition and combustion experiments showed that the Al–Mg–Si alloy fuels maintained almost the same combustion performance over a prolonged combustion time. Furthermore, the burning of the composite propellant with the Al–Mg–Si alloy as fuel was characterized by enhanced stability, a combustion cross-section with reduced clumping, and improved stability in combustion properties. Therefore, the Al–Mg–Si alloy powder can provide more reliable combustion performance and is a promising candidate for application in high-energy materials.