Mechanical properties of reactive high-entropy alloys and energy-release characteristics of projectiles impacting a multi-layer circuitry target

TiZr-based high-entropy alloys (HEAs) have emerged as promising energetic structural materials (ESMs) due to their unique combination of penetration capability and impact-induced energy-release behavior. However, a comprehensive understanding of the coupled deformation, fracture, and energy-release mechanisms in HEA-based ESMs, particularly for TiZr-based systems designed to balance mechanical strength and reactivity, remains elusive. In this work, three representative TiZr-based HEAs were fabricated via vacuum arc melting. A novel three-layer spaced target structure was designed to simulate combined metal-casing and internal circuitry systems. The underlying mechanisms governing the coupled mechanical-energetic response were investigated by integrating quasi-static and dynamic mechanical testing with post-mortem microstructural characterization and energy-release quantification. The flash duration and intensity of the energy release were further proposed as optical indicators to quantitatively characterize the impact-induced energy-release behavior of TiZr-based HEAs, where flash duration reflects the sustained energy-release capability and flash intensity represents the instantaneous energy-release intensity. The results demonstrate that TiZrNbWV exhibits the highest yield strength and superior dynamic mechanical performance, together with the most persistent energy-release behavior, whereas TiZrNbV exhibits the best plastic deformation capability and a slightly higher quasi-static fracture strength, along with the stronger instantaneous energy-release capability under low-velocity impact conditions. Ballistic tests indicate that penetration of the front aluminum (Al) plate is dominated by kinetic effects, whereas significant thermochemical energy release occurs during interaction between fragmented projectiles and the rear circuit board. Increasing impact velocity promotes projectile fragmentation and oxygen-assisted oxidation, significantly enhancing the energy-release intensity and post-penetration effects. This work provides insights into the design of HEA-based ESMs with improved mechanical and energetic performance for defense and aerospace applications.