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Enhancing the {100} grain subdivision in high-purity tantalum sheets by asymmetric cross rolling

Zhu, Jialin ; Liu, Shifeng ; Long, Doudou ; Zhou, Shiyuan ; Liu, Yahui and Orlov, Dmytro LU orcid (2020) In Materials Characterization 166.
Abstract

Weak subdivision or fragmentation ability of deformed {100} (<100> // ND, normal direction) grains by traditional unidirectional (symmetric) rolling results in uneven deformation during tantalum (Ta) processing. Thus, a recently developed asymmetric cross rolling (ACR) is adopted in this work to enhance the subdivision of {100} grain in Ta sheets. Electron backscatter diffraction (EBSD), transmission electron microscopy (TEM) and Vickers hardness (HV) were used for the characterisation of microstructure in deformed {100} grains. It is shown that added shear strain component in the ACR leads to heterogeneous deformation substructures within {100} grains. The increase of speed ratio in ACR further enhances the subdivision of... (More)

Weak subdivision or fragmentation ability of deformed {100} (<100> // ND, normal direction) grains by traditional unidirectional (symmetric) rolling results in uneven deformation during tantalum (Ta) processing. Thus, a recently developed asymmetric cross rolling (ACR) is adopted in this work to enhance the subdivision of {100} grain in Ta sheets. Electron backscatter diffraction (EBSD), transmission electron microscopy (TEM) and Vickers hardness (HV) were used for the characterisation of microstructure in deformed {100} grains. It is shown that added shear strain component in the ACR leads to heterogeneous deformation substructures within {100} grains. The increase of speed ratio in ACR further enhances the subdivision of deformed {100} grains and thus increases the density of geometrically necessary dislocations (GNDs) in them. The computation of the largest Schmid factor (SFrolling) along with Taylor model suggests that the ACR promotes easier slip within deformed {100} grains. Therefore, the necessary total shear strain contributing to the increase of GNDs density is small. By contrast, the shear strain accumulated after CR-1.0 is distributed more evenly in each slip system resulting in rather sparse distribution of dislocation lines.

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organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Asymmetric cross rolling, Electron microscopy, GNDs, Grain subdivision, Shear strain, Taylor model
in
Materials Characterization
volume
166
article number
110439
publisher
Elsevier
external identifiers
  • scopus:85086516633
ISSN
1044-5803
DOI
10.1016/j.matchar.2020.110439
language
English
LU publication?
yes
id
355cb0a7-f803-4faf-98db-4009f4362b2c
date added to LUP
2020-07-01 21:45:23
date last changed
2022-04-18 23:20:31
@article{355cb0a7-f803-4faf-98db-4009f4362b2c,
  abstract     = {{<p>Weak subdivision or fragmentation ability of deformed {100} (&lt;100&gt; // ND, normal direction) grains by traditional unidirectional (symmetric) rolling results in uneven deformation during tantalum (Ta) processing. Thus, a recently developed asymmetric cross rolling (ACR) is adopted in this work to enhance the subdivision of {100} grain in Ta sheets. Electron backscatter diffraction (EBSD), transmission electron microscopy (TEM) and Vickers hardness (HV) were used for the characterisation of microstructure in deformed {100} grains. It is shown that added shear strain component in the ACR leads to heterogeneous deformation substructures within {100} grains. The increase of speed ratio in ACR further enhances the subdivision of deformed {100} grains and thus increases the density of geometrically necessary dislocations (GNDs) in them. The computation of the largest Schmid factor (SF<sub>rolling</sub>) along with Taylor model suggests that the ACR promotes easier slip within deformed {100} grains. Therefore, the necessary total shear strain contributing to the increase of GNDs density is small. By contrast, the shear strain accumulated after CR-1.0 is distributed more evenly in each slip system resulting in rather sparse distribution of dislocation lines.</p>}},
  author       = {{Zhu, Jialin and Liu, Shifeng and Long, Doudou and Zhou, Shiyuan and Liu, Yahui and Orlov, Dmytro}},
  issn         = {{1044-5803}},
  keywords     = {{Asymmetric cross rolling; Electron microscopy; GNDs; Grain subdivision; Shear strain; Taylor model}},
  language     = {{eng}},
  month        = {{08}},
  publisher    = {{Elsevier}},
  series       = {{Materials Characterization}},
  title        = {{Enhancing the {100} grain subdivision in high-purity tantalum sheets by asymmetric cross rolling}},
  url          = {{http://dx.doi.org/10.1016/j.matchar.2020.110439}},
  doi          = {{10.1016/j.matchar.2020.110439}},
  volume       = {{166}},
  year         = {{2020}},
}