Article Ultra-grain-refinement of face-centered cubic high/medium-entropy alloys: Approaching the limit of grain refinement through severe plastic deformation and recrystallization

Shuhei Yoshida ; Nokeun Park ; Kohei Shiotani ; Yu Bai ; Tomoaki Niiyama ; Akinobu Shibata SAMURAI ORCID (National Institute for Materials Science) ; Tomotsugu Shimokawa ; Nobuhiro Tsuji

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Shuhei Yoshida, Nokeun Park, Kohei Shiotani, Yu Bai, Tomoaki Niiyama, Akinobu Shibata, Tomotsugu Shimokawa, Nobuhiro Tsuji. Ultra-grain-refinement of face-centered cubic high/medium-entropy alloys: Approaching the limit of grain refinement through severe plastic deformation and recrystallization. Materials & Design. 2025, 258 (), 114622. https://doi.org/10.1016/j.matdes.2025.114622

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(abstract)

Face-centered cubic (FCC) high- and medium-entropy alloys (HEAs/MEAs) develop fully recrystallized ultrafinegrained (FRex-UFG) microstructures after simple deformation and annealing processes. However, the mechanistic origins remain unclear. This study explains why FRex-UFG microstructures are readily formed in FCC HEAs/MEAs and clarifies their characteristics of microstructural evolution during deformation and recrystallization. CoCrFeMnNi HEA and CoCrNi MEA were subjected to high-pressure torsion (HPT) followed by short-term annealing. HPT-processed HEA and MEA showed finer nanocrystalline structures with higher dislocation densities than in conventional materials, indicating that dynamic recovery is more inhibited in HEAs/MEAs. Subsequent annealing produced FRex-UFG microstructures with grain sizes (with/without annealing twins) of 410/200 nm and 448/80 nm in the HEA and MEA, respectively, which are the smallest among single-phase materials reported to date. Grain-growth activation energies of the HEA and MEA were three times higher than that of pure Ni. Hybrid Monte‑Carlo/molecular‑dynamics simulations of grain boundary (GB) structures in model HEAs revealed that severe lattice distortion reduces GB free volume, intensifying solute drag and retarding GB migration. These results demonstrate that inhibited dynamic recovery and sluggish GB migration, both inherent to HEAs/MEAs, elevate the density of potential nuclei for recrystallization while suppressing microstructural coarsening, leading to the formation of FRex-UFG microstructures.

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Keyword: Recrystallization, Grain boundary migration, Severe plastic deformation, Deformation structure, High/Medium entropy alloys

Date published: 2025-08-22

Publisher: Elsevier BV

Journal:

  • Materials & Design (ISSN: 02641275) vol. 258 p. 114622-114622 114622

Funding:

  • Government of Japan Ministry of Education Culture Sports Science and Technology JPMXP0112101000
  • Ministry of Science, ICT and Future Planning
  • Japan Society for the Promotion of Science JP15H05767
  • Japan Society for the Promotion of Science JP22K14501
  • Japan Society for the Promotion of Science JP18H05455
  • Japan Society for the Promotion of Science JP18H05453
  • Japan Society for the Promotion of Science JP23K20037
  • Japan Society for the Promotion of Science JP25K00050
  • Japan Society for the Promotion of Science JP21K20487
  • Japan Society for the Promotion of Science JP18J20766
  • National Research Foundation of Korea
  • Ministry of Science and ICT, South Korea 2019B1801
  • Ministry of Science and ICT, South Korea RS-2024-00451579

Manuscript type: Publisher's version (Version of record)

MDR DOI:

First published URL: https://doi.org/10.1016/j.matdes.2025.114622

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Updated at: 2025-12-09 08:30:08 +0900

Published on MDR: 2025-12-09 08:24:14 +0900

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