Excellent strength-ductility combination of Cr26Mn20Fe20Co20Ni14 high-entropy alloy at cryogenic temperatures

In the present study, a face-centered cubic non-equiatomic Cr26Mn20Fe20Co20Ni14 high-entropy alloy (HEA) with a low stacking fault energy of 17.6 mJ m -2 was prepared by vacuum induction melting, forg-ing and annealing processes. The recrystallized sample is revealed to exhibit an excellent combination of strength and ductility over a wide temperature range of 4.2-293 K. With decreasing temperature from 293 to 77 K, the ductility and ultimate tensile strength (UTS) gradually increase by 30% to 95% and 137% to 1020 MPa, respectively. At the lowest temperature of 4.2 K, the ductility keeps 65% and the UTS in-creases by 200% to 1300 MPa, which exceed those published in the literature, including conventional 300 series stainless steels. Detailed microstructural analyses of this alloy reveal a change of deformation mechanisms from dislocation slip and nano-twinning at 293 K to nano-phase transformation at 4.2 K. The cooperation and competition of multiple nano-twinning and nano-phase transformation are responsible for the superior tensile properties at cryogenic temperatures. Our study provides experimental evidence for potential cryogenic applications of HEAs. (c) 2023 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.