Energy release characteristics of impact-initiated energetic aluminum–magnesium mechanical alloy particles with nanometer-scale structure

Aluminum–magnesium alloys, fabricated by bi-directional rotation ball milling, were used as a kind of promising solid fuel in “reactive material” that can be ignited by impact to release a large quantity of heats. Different percentages of Mg were added to Al to yield Al90%–Mg10% and Al70%–Mg30% alloys in order to probe the effect of Mg content on the microstructure and thermal reactivity of Al–Mg alloys. Structural characterization revealed that a nanometer-scale structure was formed and oxidation of as-fabricated alloy powders was faint. Moreover, as the Mg percentage increased, the particle size of alloy decreased with increasing brittleness of Al–Mg. TGA/DSC curves of the [Al70%–Mg30%]–O2 system exhibited an intense exothermic peak before melting with reaction heat of 2478 J g−1 and its weight increase reached 90.16% of its theoretical value, which contrasted clearly with 181.2 J g−1 and 75.35% of [Al90%–Mg10%]–O2 system, respectively. In addition, other than [Al90%–Mg10%]–Fe2O3 system, the [Al70%–Mg30%]–Fe2O3 system exhibited a considerable solid–solid reaction and a low activation energy. Finally, target penetration experiments were conducted and the results confirmed that a projectile composed of [Al70%–Mg30%]–Fe2O3 displayed a more complete ignition of target than that of Al–Fe2O3 formulation.