Enhancing cryogenic yield strength and ductility of the Al0.1CoCrFeNi high-entropy alloy by synergistic effect of nanotwins and dislocations

High-entropy alloys (HEAs) with a face-centered cubic (FCC) lattice usually exhibit decent ductility but low yield strength at cryogenic temperatures. In order to address this issue, in this study, nanotwin structures containing high-density dislocations were prepared in a typical FCC Al0.1CoCrFeNi HEA by multiaxial cryogenic forging (MACF). At 77 K, the Al0.1CoCrFeNi HEA exhibits a unique combination of high tensile yield strength of 1263 MPa and large ductility of 30% after five MACF cycles. The interplay between forging cycles and microstructures was explored, and the related strengthening mechanism related to the synergistic effect of nanotwins and dis-locations was discussed.