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.