Study on the influence of TiH₂‑doped aluminum powder on the thermal decomposition and metal‑driving performance of HMX/RDX‑based PBX explosives

The thermal decomposition and metal-driving performance of four HMX/RDX-based PBXs with varying Al/TiH₂ ratios (0–8 mass% TiH₂) were investigated. While TiH₂ addition increased particle roughness, it altered the decomposition kinetics from a first-order model to a complex function described as (− ln(1 − α))². Although the onset decomposition temperature dropped notably, the critical Self-Accelerating Decomposition Temperature (TSADT) showed only a marginal reduction, suggesting that macroscopic thermal safety remains manageable. Cylinder tests revealed that within the investigated range, the 4 mass% TiH₂ formulation (RHTL-1) enhanced the wall velocity and Gurney coefficient by 5% and 3.6% during the early expansion phase (15–30 μs), whereas higher loadings (8 mass%) shifted energy release to later stages. Consequently, comparing the metallized formulations, 4 mass% TiH₂ offers the most favorable trade-off between early metal-drive capability and energy release characteristics.