Abstract: The Fe₄₀Mn₁₀Cr₂₅Ni₂₅ high-entropy alloy (HEA) with partial recrystallization was prepared by cold rolling and subsequent annealing. The tensile properties of the alloy at room temperature (298 K) and cryogenic temperature (77 K) were studied. The results show that the alloy has excellent room temperature and cryogenic temperature mechanical properties. Both the strength and ductility of the alloy are improved under tension at cryogenic temperature. The strength and percentage elongation after fracture at room temperature are 880 MPa and 18% respectively, and 1360 MPa and 36% respectively at 77 K. The tensile deformation of the alloy at room temperature is dominated by dislocation slip, but by dislocation slip and twinning at cryogenic temperature. The coarse grains deform before fine grains under tensile stress at room temperature, resulting in a strain gradient inside the specimen, so that the work hardening rate of the alloy is increased, the alloy exhibits excellent combination of strength and ductility at room temperature. A large quantity of high-density deformation twins are formed in the coarse grains under tensile stress at cryogenic temperature, so that the cryogenic temperature mechanical properties of the alloy can be improved.

Key words: high-entropy alloy, microstructure, mechanical properties, dislocation, twin