Developing Fast-Reacting Metallic Composites as Additives to Explosives

Research into fast-reacting energy-dense additives for CHNO explosives like Octogen (HMX) continues, as pure metal powders react too slowly compared to fast events such as detonations

spanning tens of nanoseconds. The heterogeneous, diffusion-limited combustion of metals like aluminum delays their energetic contribution by microseconds to milliseconds. Replacing

aluminum powder with Arrested Reactive Milled (ARM) composites containing nanometrically mixed aluminum and oxidizer inclusions have shown promise. These homogeneous fuel-oxidizer

systems, with extended reactive interfaces, exhibit shear-driven reactions with nanosecond onsets. ARM enables tailoring composite properties by adjusting parameters such as milling time, process-control agent composition and volume, vial agitation RPM, and ball-to-powder ratio among others. Resulting in a wide range of powder properties such as size distribution, shape, surface morphology, porosity, and scale of fuel-oxidizer mixing. To explore the link between powder nanostructure and reactivity in this vast parametric space, we developed a high-throughput test using a tabletop laser-driven flyer plate to shock micron-scale samples. Reactivity is captured using a high-speed camera with 3 μm spatial resolution and, 3 ns temporal resolution. While a calibrated 32-channel spectrometer tracks emissions in the visible range to yield spatially averaged temperatures and radiance. The powder batch that reacts fast compared to HMX is chosen amongst the batches prepared to isolate the nanostructural features that sensitize composites to shock compression.