Structural Modifying Effect of Magnesium on Enhancing Oxidation and Combustion Performance of Aluminum-Lithium Alloys

To address the challenges of poor chemical stability and safety hazards in aluminum-lithium (Al-Li) alloys with high Li content for metal fuel applications, this study pioneers a ternary Al-Li-Mg system, synergistically optimizing structure and oxidation/combustion. The spherical Al-Li-Mg alloy powders (3 wt.% Li, 10 and 20 wt.% Mg) were prepared via high-speed centrifugal atomization. Composition and structural characterization revealed a hierarchical structure: an α-Al matrix with interconnected channels enriched in Al3Mg2 and Al2LiMg intermetallics. Compared to Al-Li alloys, the ternary alloying significantly lowered the initial oxidation temperature by 125.2°C in thermogravimetric-differential thermal analysis and enabled staged heat release. Combustion in perchlorate composites showed shortened ignition delays, and AlLi3Mg20/KP achieved a 3.22 mm/s burning rate with intensified gas-phase reactivity and smaller residues. Mg enables dual-stage melting-oxidation, disrupting the passivation layer for complete core combustion while suppressing Al agglomeration. These synergistic effects concurrently shorten ignition delays and elevate combustion efficiency. This work establishes a theoretical and technological framework for advancing the compositional design and performance optimization of high-energy metal fuels.