Effect of Annealing on Microstructure Evolution and Tensile Behavior of Hot-Rolled FeMnCoCrAl High-Entropy Alloy

In this study, a new composition of HEA ((Fe 50 Mn 30 Co 10 Cr 10 ) 91 Al 9 , at.%) was designed, and the microstructure evolution and tensile behavior of hot-rolled (Fe 50 Mn 30 Co 10 Cr 10 ) 91 Al 9 (at.%) high-entropy alloy (HEA) were investigated after annealing at various temperatures. The HEA exhibited a three-phase structure of the FCC phase, BCC phase, and a small amount of HCP phase after hot rolling and annealing. Annealing at lower temperatures led to a higher fraction of BCC phase and sub-crystalline grains in the recovery state, making the HEA have high strength. After annealing at high temperatures, the fraction of FCC phase increased. The fraction of recrystallized grains and twin boundaries in the HEA also increased, improving the ductility of the HEA. The HEA exhibited a multistage strain-hardening mechanism during deformation, which was rarely seen in traditional HEAs. The relationship between the microstructure and mechanical properties was discussed from the lattice frictional stress, solid solution strengthening, phase fractions, grain sizes, and dislocation.