Disordering of L12 Phase in High-Entropy Alloy Deformed at Cryogenic Temperature

Recently, novel high-entropy alloys (HEAs) of Al–Co–Cr–Fe–Ni–Ti systems containing face-centered cubic (FCC) matrix and γ′ precipitates (L12 phase) have been studied. They show superior mechanical properties at room (298 K) and cryogenic temperatures (77 K). Herein, microstructure deformation and fracture after tensile strain are investigated. The results show that multiple-layered stacking faults occur after the tensile test at 77 K, which can increase the yield strength and ultimate tensile strength by 20% and 24%, respectively. The γ′ precipitates become disordered after the alloy deforms at 77 K, which decreases the formation barrier of mechanical twinning and increases ductility at 77 K by 27%. ? 2021 Wiley-VCH GmbH