Abstract:As an emerging structural material, high-entropy alloys (HEAs) have significant application potential in high-strain-rate environments and across a range of temperatures, including both high and low temperatures. Previous studies mainly focused on the mechanical behavior of HEAs under high-speed loading or low temperature, which is limited to a single extreme environment. This paper primarily discusses the mechanical behavior and microscopic mechanism of the Fe40Mn20Cr20Ni20 high-entropy alloy (HEA) at high and low temperatures and high strain rates (Split Hopkinson bar) and utilizes relevant theoretical models to fit the yield strength and flow stress of the HEA. The tensile test results show that the HEA exhibits excellent strength-plastic synergy and excellent work-hardening ability under the condition of reducing temperature or increasing strain rates. During the dynamic tensile process, the interaction of different forms of dislocations and deformation twins together improves the strength and work-hardening ability of the HEA. The Zerilli-Armstrong (Z-A) constitutive model was used to predict the temperature sensitivity and strain-rate sensitivity of the yield strength of the HEA. At the same time, the Taylor model was used to predict the change of the HEA flow stress with the strain rate under dynamic tension, and the model was applied to low-temperature dynamics. The fitting results were consistent with the experimental results, which provided a theoretical basis for the subsequent prediction of HEAs strengths.