Role of Nanostructural Features in Shock-initiated Reactivity of Milled Composite

To improve the detonation characteristics of conventional CHNO energetics, such as Octogen (HMX), energy-dense additives like aluminum powder are of interest. However, aluminum’s sluggish combustion limits its energy release to the post-detonation afterburn rather than the rapid detonation event, which spans tens of nanoseconds. Additionally, aluminum can cannibalize valuable intermediate species formed during explosive decomposition. To address these limitations, we are developing arrested reactive milled (ARM) composites as additives, which incorporate oxidizers mixed with the fuels at the nanometric scale. This approach reduces the material and energy dependence of the additive on the surrounding detonating mixture. Using ARM, we can tailor powder attributes, such as shape and size distributions, as well as its nanostructural features such as degree of fuel-oxidizer mixing and porosity for several fuel-oxidizer compositions. The resulting parameter space requires optimization to identify powders with attributes that promote fast combustion within the deflagration/detonation timescales observed in HMX, which serves as our benchmark. To assess their performance, we use high-throughput laser-launched flyers to shock individual particles from several composite batches. By suspending single particles in transparent polymer wells, we isolate particle-scale behavior from the complex effects of packing microstructure. The reactive behavior is visually tracked using a high-speed camera with a spatial resolution of 3 μm and a temporal resolution of 3 ns. Meanwhile, a calibrated 32-channel spectrometer acquiring an intensity snapshot every 0.8 ns, serving as our spatially averaged pyrometer. Composites deemed interesting as prospective additives through this process will be tested with HMX to observe shock response in comparison to HMX and aluminized HMX samples.