Optimizing Ball‐Milled Composites for Fast Energy Release Under Shock Compression

ABSTRACT Microparticle additives containing both Al fuel and oxidizer, fabricated by arrested reactive milling (ARM), could potentially increase the power of energetic materials such as HMX because they contain premixed fuel and oxidizer. Optimizing shock reactivity requires exploring a vast parametric space encompassing composition, milling parameters that govern microstructural features such as intraparticle voids and fuel‐oxidizer mixing, and the resulting inhomogeneous shock reactivity of individual particles. To present our approach, we used a model composition 8Al·3CuO, previously optimized for combustion. We milled powders and prescreened different prepared batches using differential scanning calorimetry (DSC) to rule out batches with significant pre‐reaction. Then we employed high‐throughput tabletop shock testing. Each experiment shocked hundreds of individual microparticles embedded in a transparent polymer binder by a flyer impacting at 3.5 km/s (17 GPa). Thermal emission detected with nanosecond and micrometer‐resolution measured hot spot and combustion temperatures, energy output, and energy release rates as a function of particle size. In the initial experiments, the milling conditions that produced larger oxide inclusions resulted in hotter hot spots, higher combustion temperatures, and greater energy output. Driven by shock‐induced reactions, these microparticles underwent volume explosion.