An equiatomic VCoNi medium-entropy alloy possesses high sensitivity to grain-boundary strengthening, achieved by severe lattice distortions. Its ultrafine-grain structure enables 1.5 Gigapascal yield strength even for the fully recrystallized alloy with a single face-centered cubic structure. The high density of grain boundaries also generates high back stresses via piling up of massive dislocations, and the low cross-slip probabilities produce not only robust dislocation-mediated plasticity but also high back stress contribution to flow stress, which affords high strain-hardening capability to ultrafine-grain alloys, with 1.7 Gigapascal ultimate tensile strength with remarkable ductility. Our approach provides a new method for developing ultrastrong metallic materials.
Bibliographical noteFunding Information:
This work was supported by the National Research Foundation of Korea (grant number?NRF-2020R1C1C1003554); the Creative Materials Discovery Program of the NRF?funded by the Ministry of Science and ICT [grant number NRF-2016M3D1A1023384]; the Korea Institute for Advancement of Technology (KIAT) grant funded by the Korean Government (MOTIE) [grant number P0002019, The Competency Development Program for Industry Specialist]. J.M. Park is also supported by the Basic Science Research Program ?Fostering the Next Generation of Researchers? through the NRF funded by the Ministry of Education [grant number 2020R1A6A3A13073260].
© 2021 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.
- Medium-entropy alloy
- grain boundary strengthening
- severe lattice distortion
- severe plastic deformation
- ultrafine grain structure
ASJC Scopus subject areas
- General Materials Science