A cost-effective cryogenic high-entropy alloy with high strength-ductility synergy and strain hardenability
Yu Yin, Wangrui Ren, Qiyang Tan, Houwen Chen, Han Huang, Mingxing Zhang
Abstract
High entropy alloys (HEAs) with a face-centred cubic (FCC) matrix usually exhibit exceptional cryogenic mechanical properties. However, their industrial applications are limited due to their high cost resulted from the use of expensive elements, including Co, V, etc. In this work, a cost-effective HEA, Fe35Ni35Cr20Mo5Al5, with a single FCC matrix is developed, aiming at enhancing the application potential of cryogenic FCC-HEAs. The HEA showed a temperature-dependent tensile properties. Its yield strength and tensile strength were increased from ∼302 MPa to 455 MPa and from ∼673 to ∼952 MPa with ductility increased from ∼68% to ∼84% when the temperature was decreased from 298 K to 77 K. In particular, the steady-state strain hardening rate was ∼2 GPa at 77 K, which is twice of that at 298 K. Compared with previously reported cryogenic HEAs, the new alloy has a relatively low raw materials cost but possesses a superior strain hardening capacity and exceptional strength-ductility synergy at 77 K. Its excellent property is ascribed to the formation of a complicated nanoscale twin network and its extensive interaction with dislocations. The combination of relatively low raw materials cost and superior cryogenic mechanical properties make this HEA a promising material candidate for cryogenic applications.