Dynamic response and impact energy release mechanism of (Ti₂Zr)_1.5NbVAl_0.5 high-entropy alloy

To overcome the limitations of traditional metallic materials regarding energy-release efficiency under high-velocity impact, this study designed and fabricated a novel single-phase body-centered cubic (BCC) structured lightweight refractory high-entropy alloy (Ti₂Zr)_1.5NbVAl_0.5. The investigation employed a combined approach of multi-scale experimentation and numerical simulation. The as-cast microstructure was characterized, revealing a homogeneous composition with an average grain size of 336.7 μm. Quasi-static and dynamic mechanical tests were conducted to evaluate strength, plasticity, and strain-rate sensitivity, providing data to fit the Johnson-Cook constitutive and damage parameters. Direct ballistic experiments were conducted at impact velocities of 734, 950, and 1375 m/s to analyze fragmentation behavior, temperature evolution, and energy release within a quasi-confined chamber. A coupled finite element method-smoothed particle hydrodynamics (FEM-SPH) numerical model was developed to simulate the penetration process, successfully replicating experimental temperature rises and fragmentation patterns. The results showed that the alloy possesses an excellent strength-plasticity synergy and remarkable strain-rate sensitivity, with yield strength increasing by 123% to 1977.3 MPa at 6000 s⁻¹. Ballistic tests demonstrated that increased impact velocity intensified fragmentation and energy release, achieving a peak chamber temperature of 2124.15 K and extending the release duration to 12 ms at 1375 m/s. Microstructural analysis revealed that the energy release mechanism is governed by dislocation dynamics within adiabatic shear bands (ASBs). At lower impact velocities (e.g., 734 m/s), dynamic recrystallization in ASBs alleviates strain hardening. In contrast, at high velocities (e.g., 1375 m/s), suppressed cross-slip leads to dislocation saturation, local lattice instability, and ultimately severe fragmentation coupled with exothermic oxidation. The study concludes that (Ti₂Zr)_1.5NbVAl_0.5 high-entropy alloy exhibits outstanding dynamic properties and controllable impact-induced energy release, primarily driven by velocity-dependent microstructural evolution in ASBs, demonstrating significant potential as a new-generation energetic structural material for extreme dynamic loading applications.