Atomistic Insights into the Radiation-Induced Damage Mechanisms of CL-20: Effects on Shock Sensitivity and Detonation...

Aging and performance degradation of energetic materials (EMs) under radiation are critical issues affecting the reliability of energetic systems. In this study, we employed molecular dynamics simulations based on the Multi-Scale Shock Technique (MSST), integrated with the ReaxFF-lg/ZBL force field, to elucidate the shock-to-detonation transition (SDT) mechanisms of ε-CL-20 crystals under various irradiation doses (0-6.5 × 10^-3 dpa). The results reveal that a coupled physicochemical mechanism governs the material response. Irradiation-induced defects, particularly gas-filled voids, transitioned the shock response from homogeneous shear band formation to localized hotspot generation. This transition shortened ignition delay times and sensitized the material at low-to-medium doses. However, the accumulation of defects altered reaction pathways, introducing a competition between activation entropy and reaction barriers. At high doses, severe structural degradation led to insufficient C-N bond scission, resulting in the formation of nitroamine intermediates and large carbonaceous clusters that hindered further reactions; consequently, the sensitivity followed a nonmonotonic trend, first increasing and then decreasing with dose. Detonation performance calculations demonstrate that although irradiation damage enhanced early-stage reaction rates, the final Chapman-Jouguet (C-J) detonation pressure decreased by over 20%. We identify a failure threshold above which the ε-CL-20 crystal loses its ability to sustain a detonation wave, degrading into a decoupled shock-deflagration mode. These insights provide a comprehensive atomic-scale theoretical basis for understanding the radiation damage and failure mechanisms of nitramine explosives.