Excellent combination of cryogenic-temperature strength and ductility of high-entropy-alloy-cored multi-layered sheet

We newly design a high-entropy-alloy(HEA)-cored multi-layered sheet (MLS) containing AISI 304 stainless steel (STS) surface layers (HEA/STS MLS) by using a commercial roll-bonding procedure, and property-enhancing mechanisms such as TWinning Induced Plasticity (TWIP), TRansformation Induced Plasticity (TRIP), and geometrically necessary dislocation (GND) generation were analyzed. This MLS well satisfied a rule of mixtures because the HEA and STS layers were strongly bonded to show similar deformation mechanisms of TWIP and TRIP at both room and cryogenic temperatures. The HEA layer demonstrated synergic effects of homogenization and maximization of TWIP and TRIP mechanisms with the STS layers. In particular, very high strain hardening and persistent elongation (about 50%) as well as very high tensile strength over 1.5 GPa are quite unique and interesting results because they have not been reported in the FCC-based HEA areas yet. Our findings also demonstrate that the HEA-cored MLS fabrication can be an attractive route to a new HEA design strategy for cryogenic applications.