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  Dislocation-induced breakthrough of strength and ductility trade-off in a non-equiatomic high-entropy alloy

Guo, W., Su, J., Lu, W., Liebscher, C., Kirchlechner, C., Ikeda, Y., et al. (2020). Dislocation-induced breakthrough of strength and ductility trade-off in a non-equiatomic high-entropy alloy. Acta Materialia, 185, 45-54. doi:10.1016/j.actamat.2019.11.055.

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Item Permalink: http://hdl.handle.net/21.11116/0000-0006-0D09-3 Version Permalink: http://hdl.handle.net/21.11116/0000-0006-0D0A-2
Genre: Journal Article

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 Creators:
Guo, Wenqi1, Author              
Su, Jing2, Author              
Lu, Wenjun1, Author              
Liebscher, Christian1, Author              
Kirchlechner, Christoph3, Author              
Ikeda, Yuji4, Author              
Körmann, Fritz5, 6, Author              
Liu, Xuan7, Author              
Xue, Yunfei7, Author              
Dehm, Gerhard8, Author              
Affiliations:
1Advanced Transmission Electron Microscopy, Structure and Nano-/ Micromechanics of Materials, Max-Planck-Institut für Eisenforschung GmbH, Max Planck Society, ou_1863399              
2High-Entropy Alloys, Microstructure Physics and Alloy Design, Max-Planck-Institut für Eisenforschung GmbH, Max Planck Society, ou_3010672              
3Nano-/ Micromechanics of Materials, Structure and Nano-/ Micromechanics of Materials, Max-Planck-Institut für Eisenforschung GmbH, Max Planck Society, ou_1863401              
4Computational Materials Design, Max-Planck-Institut für Eisenforschung GmbH, Max Planck Society, ou_1863337              
5Computational Phase Studies, Computational Materials Design, Max-Planck-Institut für Eisenforschung GmbH, Max Planck Society, ou_1863341              
6Department of Materials Science and Engineering, Delft University of Technology, Mekelweg 2, 2628 CD Delft, The Netherlands, ou_persistent22              
7School of Materials Science and Engineering, Beijing Institute of Technology, Beijing 100081, China, ou_persistent22              
8Structure and Nano-/ Micromechanics of Materials, Max-Planck-Institut für Eisenforschung GmbH, Max Planck Society, ou_1863398              

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Free keywords: Calculations; Chromium alloys; Cobalt alloys; Deformation; Dislocations (crystals); Ductility; Economic and social effects; Entropy; Grain refinement; Grain size and shape; High-entropy alloys; Iron alloys; Stacking faults; Strain hardening; Tensile strength, Dislocation cell structures; Dominant deformation mechanism; First-principles calculation; Stacking fault energies; Strength and ductilities; Strength-ductility synergies; Trade off; Ultimate tensile strength, Manganese alloys
 Abstract: In conventional metallic materials, strength and ductility are mutually exclusive, referred to as strength-ductility trade-off. Here, we demonstrate an approach to improve the strength and ductility simultaneously by introducing micro-banding and the accumulation of a high density of dislocations in single-phase high-entropy alloys (HEAs). We prepare two compositions (Cr10Mn50Fe20Co10Ni10 and Cr10Mn10Fe60Co10Ni10) with distinctive different stacking fault energies (SFEs) as experimental materials. The strength and ductility of the Cr10Mn50Fe20Co10Ni10 HEA are improved concurrently by grain refinement from 347.5 ± 216.1 µm to 18.3 ± 9.3 µm. The ultimate tensile strength increases from 543 ± 4 MPa to 621 ± 8 MPa and the elongation to failure enhances from 43±2 to 55±1. To reveal the underlying deformation mechanisms responsible for such a strength-ductility synergy, the microstructural evolution upon loading is investigated by electron microscopy techniques. The dominant deformation mechanism observed for the Cr10Mn50Fe20Co10Ni10 HEA is the activation of micro-bands, which act both as dislocation sources and dislocation barriers, eventually, leading to the formation of dislocation cell structures. By decreasing grain size, much finer dislocation cell structures develop, which are responsible for the improvement in work hardening rate at higher strains (gt;7) and thus for the increase in both strength and ductility. In order to drive guidelines for designing advanced HEAs by tailoring their SFE and grain size, we compute the SFEs of Cr10MnxFe70–xCo10Ni10 (10 ≤ x ≤ 60) based on first principles calculations. Based on these results the overall changes on deformation mechanism can be explained by the influence of Mn on the SFE. © 2019 Acta Materialia Inc.

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Language(s): eng - English
 Dates: 2020-02-15
 Publication Status: Published in print
 Pages: -
 Publishing info: -
 Table of Contents: -
 Rev. Method: -
 Identifiers: DOI: 10.1016/j.actamat.2019.11.055
 Degree: -

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Title: Acta Materialia
  Abbreviation : Acta Mater.
Source Genre: Journal
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Publ. Info: Kidlington : Elsevier Science
Pages: - Volume / Issue: 185 Sequence Number: - Start / End Page: 45 - 54 Identifier: ISSN: 1359-6454
CoNE: https://pure.mpg.de/cone/journals/resource/954928603100