Ultra-strong and strain-hardenable ultrafine-grained medium-entropy alloy via enhanced grain-boundary strengthening

Jeong Min Park, Dae Cheol Yang, Han Jin Kim, Dong Geun Kim, Sunghak Lee, Hyoung Seop Kim, Seok Su Sohn

Research output: Contribution to journalArticlepeer-review

Abstract

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.

Original languageEnglish
Pages (from-to)315-321
Number of pages7
JournalMaterials Research Letters
Volume9
Issue number7
DOIs
Publication statusPublished - 2021

Keywords

  • grain boundary strengthening
  • Medium-entropy alloy
  • severe lattice distortion
  • severe plastic deformation
  • ultrafine grain structure

ASJC Scopus subject areas

  • Materials Science(all)

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