Study on the Thermal Deformation Behavior and Hot Processing Map of FeCoNiCuB0.1Si0.16 High-Entropy Alloy

The Gleeble-3500 thermal simulation testing machine was utilized to acquire the true stress–true strain curves of the FeCoNiCuB_0.1Si_0.16 high-entropy alloy (HEA) within the range of strain temperatures from 1123 to 1323 K and strain rates of 0.05 s^-1, 1 s^-1, 2 s^-1. Employing the Arrhenius model, we formulated the constitutive equation of the HEA alloy under a strain flow stress of 0.5, subsequently determining the deformation activation energy and material parameters across different strain conditions. By utilizing strain ε as the independent variable, the material constants were fitted using a fourth-order polynomial, and the validity of the constitutive equation was verified. According to the power dissipation theory and the instability criterion of the dynamic material model, we constructed a power dissipation diagram and an instability diagram, subsequently overlaying the two to generate a hot processing map at a strain of 0.5. These findings indicate that the flow stress of the HEA alloy escalates with an increase in strain rate and stabilizes after reaching its peak, showcasing typical dynamic recovery characteristics. Moreover, at strain temperatures surpassing 1243 K, the alloy exhibits dynamic recrystallization traits. The hot processing map reveals that within the region of strain temperatures ranging from 1243 to 1323 K and strain rates from 10^−1.3 to 10^0.3, the high-power parameter η > 0.3, whereas the unstable region predominantly concentrates in the lower strain temperature range. Hence, when selecting thermal deformation parameters, one should actively avoid this area.