Al-based alloys (Al–Ti, Al–Zr, Al–Mo) in composite propellants: multifaceted optimization of combustion and energetics

To address space constraints in solid rocket motors, this study investigates Al–Ti, Al–Zr, and Al–Mo alloys. Their high density enhances energy release per unit volume. Multidimensional analyses—thermal oxidation behavior, ignition/combustion characteristics, and agglomeration properties—were conducted to elucidate how high-density alloys influence Al-based propellant combustion performance and energy release. Results show these high-density alloys exhibit shorter ignition delay time and combustion time, effectively increasing the propellant burning rate of propellants while reducing the pressure exponent. Titration measurements reveal combustion efficiencies of 84.28% (A), 87.33% (AT), 86.79% (AZ), and 85.91% (AM). Among them, Al–Zr demonstrates the most significant optimization effect on combustion performance. Due to the low ignition threshold, Al–Ti significantly suppresses agglomerate formation and accelerates the combustion. Meanwhile, Al–Mo enhances the transport efficiency of oxidizing gases through the phase-change sublimation mechanism of MoO 3 , indirectly boosting combustion efficiency. Furthermore, this work reveals the synergistic mechanisms by which high-density alloys optimize propellant combustion performance via multiple factors. The findings confirm the technical feasibility of simultaneously achieving superior combustion performance, high energy output, and effective agglomeration suppression, providing theoretical and technological guidance for developing advanced high-energy-density solid propellants.