High Strength and Ductility in Partially Recrystallized Fe40mn20cr20ni20 High-Entropy Alloys at Cryogenic Temperature

The effects of cold rolling and subsequent annealing on the microstructures and mechanical properties of Fe 40 Mn 20 Cr 20 Ni 20 high-entropy alloys (HEAs) were investigated. The Cr-rich secondary phases with a tetragonal structure (sigma phase) in the Fe 40 Mn 20 Cr 20 Ni 20 HEA were precipitated upon annealing at 600°C - 900 °C for 2h. The prepared Fe 40 Mn 20 Cr 20 Ni 20 HEA annealed at 800 °C for 2 h after cold rolling has a good combination of strength and elongation, with a high yield strength of 438 MPa, a high ultimate tensile strength of 676 MPa, and an excellent elongation to fracture of 32%. The mechanical properties at cryogenetic temperature are better than those at room temperature. Typically, for the incompletely-recrystallized alloy annealed at 700℃, the yield strength, tensile strength, and elongation after fracture are increased by 1.26, 1.22, and 2 times, respectively. This trend mainly depends on the dislocation and twinning strengthening. Besides, the sigma (σ) phases also improve cryogenic tensile properties. Furthermore, the recrystallization kinetics of the Fe 40 Mn 20 Cr 20 Ni 20 HEA is explored to correlate the deformation behavior