Revealing microstructure evolution in Fe₃₆Ni₃₆Al₁₇Cr₁₀Mo₁ eutectic high entropy alloy over a wide range of strain rate at 1180 ℃

Eutectic high entropy alloys (EHEAs) have received extensive attention owing to their excellent liquidity and comprehensive mechanical properties. Hot processing serves not only as a central process to tailor the microstructure and properties of metallic materials but also as a critical step toward massive fabrication. In this work, the microstructure evolution and dynamic softening mechanisms of the Fe₃₆Ni₃₆Al₁₇Cr₁₀Mo₁ EHEA were studied via hot compression tests at 1180 ℃/0.05 s⁻¹ and 1180 ℃/5 s⁻¹. The initial microstructures in both face-centered-cubic (FCC) and B2 phases contained relatively low fraction of high angle grain boundaries (HAGBs) after homogenization. For low and high strain rates, the FCC phase presented discontinuous dynamic recrystallization (DDRX), while the DDRX process exhibited obvious differences in nucleation and growth. The B2 phase showed a stronger dynamic recovery capability. Consequently, the B2 phase underwent softening via continuous dynamic recrystallization (CDRX) at both strain rates. The misorientation distribution of the lamellar and irregular structures in each phase revealed that recrystallization occurred preferentially within the irregular structure in both phases. This work provided important guidance for understanding the microstructure selection in industrial preparation of EHEAs.