Numerical and experimental study on impact-induced energy release characteristics of Ti-Zr-Hf-Ta energetic high entropy alloy

Energetic high entropy alloys (EHEAs) are a novel type of energetic structural materials (ESMs) that integrate both structural strength and chemical reactivity. They have attracted widespread attention in the military field due to their combustion characteristics under impact loading. However, the impact-induced energy release behavior of EHEAs involves complex processes and mechanisms, making it challenging to track the key parameters. In this study, the impact-induced energy release characteristics of a Ti-Zr-Hf-Ta EHEA were systematically investigated through experimental and numerical approaches. The Johnson-Cook constitutive and damage models were determined to describe the alloy's dynamic fragmentation behavior. Furthermore, a numerical model was established by calculating the mass of fragments that meet combustion reaction conditions. This model demonstrated high accuracy, with an average deviation of 8.77% from the experimental results. The results show that both the energy release efficiency and fragmentation degree increase with impact velocity, though the efficiency gains diminish at higher velocities due to limited further deformation and fragmentation. Chemical composition analysis confirmed that the energy release originates from severe oxidation of high-temperature fragments, initiated by active elements (Zr, Hf, Ti) and subsequently promoted Ta oxidation. During the penetration process, the combined effects of compression and tensile waves led to initial fracture at the projectile's front, followed by internal cracking. The tensile-compressive asymmetry of ESMs is identified as a key factor influencing their post-penetration energy release efficiency. This work provides a reliable numerical method for predicting the impact-induced energy release of ESMs and deepens the understanding of their energy release mechanisms.