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Recovery plays distinct roles in nanostructured and coarse-grained metallic materials. While static and dynamic recovery usually soften work-hardened, coarse-grained materials, static recovery has been shown to strengthen nanostructured metals. This study extends this understanding by demonstrating that dynamic recovery can also strengthen nanostructured metals under deformation. Tensile, creep, and plane strain compression tests on nanostructured aluminum reveal a trend of increasing strain-hardening with decreasing strain rate and increasing temperature. Molecular dynamics simulations further indicate that sudden strain rate reductions lead to an initial drop in flow stress, followed by strain hardening. These findings suggest that dynamic recovery could serve as an effective strengthening mechanism for nanostructured metals, offering improvements in uniform elongation.
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Atomic faulting induced exceptional cryogenic strain hardening in gradient cell–structured alloy
Coarse-grained materials are widely accepted to display the highest strain hardening and the best tensile ductility. We experimentally report an attractive strain hardening rate throughout the deformation stage at 77 kelvin in a stable single-phase alloy with gradient dislocation cells that even surpasses its coarse-grained counterparts. Contrary to conventional understanding, the exceptional strain hardening arises from a distinctive dynamic structural refinement mechanism facilitated by the emission and motion of massive multiorientational tiny stacking faults (planar defects), which are fundamentally distinct from the traditional linear dislocation–mediated deformation. The dominance of atomic-scale planar deformation faulting in plastic deformation introduces a different approach for strengthening and hardening metallic materials, offering promising properties and potential applications.
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- Award ID(s):
- 1809640
- PAR ID:
- 10553116
- Publisher / Repository:
- AAAS
- Date Published:
- Journal Name:
- Science
- Volume:
- 382
- Issue:
- 6667
- ISSN:
- 0036-8075
- Page Range / eLocation ID:
- 185 to 190
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1126/science.adj3974
