Abstract: This study synthesized a high-strength Zr₄₂Ti₁₅Nb₂₀Ta₂₀Al₃ (at.%) refractory high-entropy alloy (RHEA) via vacuum induction melting. The mechanical behavior of the Zr₄₂Ti₁₅Nb₂₀Ta₂₀Al₃ RHEA was systematically investigated through a universal testing machine and split Hopkinson pressure bar system at strain rates up to 5100 s^-1, and the temperature change is from 193 K to 673 K. By integrating theoretical derivation and microstructural characterization, we examined the mechanical behavior and deformation mechanisms of the Zr₄₂Ti₁₅Nb₂₀Ta₂₀Al₃ RHEA under the synergistic effects of temperature and strain rate. The results demonstrate that the Zr₄₂Ti₁₅Nb₂₀Ta₂₀Al₃ RHEA exhibits a significant positive strain rate effect. The dominant deformation mechanism changes with increasing strain rate: cross-slip → localized shear → adiabatic shear. When the strain rate reaches 5100 s^-1, the yield strength increases from 1151 MPa to 2112 MPa, and an adiabatic shear band forms. Simultaneously, the microstructure undergoes severe localized deformation, dominated by shear bands, and dynamic recrystallization (DRX) is activated to counteract the deformation. At 193 K, the yield strength is 2241 MPa. Kink bands have appeared, enhancing the ductility of RHEA: the yield strength and the temperature sensitivity coefficient decrease with increasing temperature. However, as the temperature increases, atomic mobility is enhanced, which promotes grain boundary sliding and migration, activating DRX, and effectively mitigating shear localization. This study deepens our understanding of the mechanical properties and deformation mechanisms of the Zr₄₂Ti₁₅Nb₂₀Ta₂₀Al₃ RHEA. It reveals the microstructure evolution process of the alloy under different strain rates, the synergistic effect of strain rate and temperature, and the influence of strain rate and temperature on the deformation mechanisms of the material. This research lays a theoretical foundation for applying the Zr₄₂Ti₁₅Nb₂₀Ta₂₀Al₃RHEA in extreme environments.

Key words: Refractory high entropy alloy, Temperature effect, Strain rate, Mechanical properties, Deformation mechanism