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Characterization of defect microstructure in MgRE (RE=Ce, Nd) alloys after processing by high-pressure torsion using positron annihilation spectroscopy and a high resolution X-ray diffraction

Bibimoune, I. ; Bourezg, Y. I. ; Abib, K. ; Liedke, M. O. ; Wagner, A. ; Matej, Z. LU orcid ; Huang, Y. ; Langdon, T. G. and Bradai, D. (2023) In Physica B: Condensed Matter 663.
Abstract

Two MgRE (RE = Ce, Nd) alloys with ultrafine-grain (UFG) microstructures were prepared by high-pressure torsion (HPT) at room temperature. The in-depth distribution of defects was characterized by Doppler broadening –variable energy positron annihilation spectroscopy (DB-VEPAS). The characteristic S parameter increases in bulk after HPT processing relative to an as-received sample and shows a relative stability between ½ and 10 turns, which suggests a rise in the open volume defect density. However, a theoretical analysis of the S(E) depth profile reveals an increase in the positron diffusion length from ∼115 nm for the as-received state to ∼207 nm after 10 HPT turns. Almost all the open volume defect consisted of dislocations (positron... (More)

Two MgRE (RE = Ce, Nd) alloys with ultrafine-grain (UFG) microstructures were prepared by high-pressure torsion (HPT) at room temperature. The in-depth distribution of defects was characterized by Doppler broadening –variable energy positron annihilation spectroscopy (DB-VEPAS). The characteristic S parameter increases in bulk after HPT processing relative to an as-received sample and shows a relative stability between ½ and 10 turns, which suggests a rise in the open volume defect density. However, a theoretical analysis of the S(E) depth profile reveals an increase in the positron diffusion length from ∼115 nm for the as-received state to ∼207 nm after 10 HPT turns. Almost all the open volume defect consisted of dislocations (positron lifetime of τ = 260 ps). The dislocation density deduced from high-resolution X-ray diffraction in the HPT disc radial direction was reasonably homogeneous (around 4–6 × 1014 m−2).

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organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Dislocations, HPT, Mg, Positron, Rare earth, Spectroscopy
in
Physica B: Condensed Matter
volume
663
article number
414963
publisher
Elsevier
external identifiers
  • scopus:85162254362
ISSN
0921-4526
DOI
10.1016/j.physb.2023.414963
language
English
LU publication?
yes
id
a06effd6-2a02-4abe-bd03-6b84aa67e82c
date added to LUP
2023-09-05 13:21:15
date last changed
2023-09-05 13:21:15
@article{a06effd6-2a02-4abe-bd03-6b84aa67e82c,
  abstract     = {{<p>Two MgRE (RE = Ce, Nd) alloys with ultrafine-grain (UFG) microstructures were prepared by high-pressure torsion (HPT) at room temperature. The in-depth distribution of defects was characterized by Doppler broadening –variable energy positron annihilation spectroscopy (DB-VEPAS). The characteristic S parameter increases in bulk after HPT processing relative to an as-received sample and shows a relative stability between ½ and 10 turns, which suggests a rise in the open volume defect density. However, a theoretical analysis of the S(E) depth profile reveals an increase in the positron diffusion length from ∼115 nm for the as-received state to ∼207 nm after 10 HPT turns. Almost all the open volume defect consisted of dislocations (positron lifetime of τ = 260 ps). The dislocation density deduced from high-resolution X-ray diffraction in the HPT disc radial direction was reasonably homogeneous (around 4–6 × 10<sup>14</sup> m<sup>−2</sup>).</p>}},
  author       = {{Bibimoune, I. and Bourezg, Y. I. and Abib, K. and Liedke, M. O. and Wagner, A. and Matej, Z. and Huang, Y. and Langdon, T. G. and Bradai, D.}},
  issn         = {{0921-4526}},
  keywords     = {{Dislocations; HPT; Mg; Positron; Rare earth; Spectroscopy}},
  language     = {{eng}},
  publisher    = {{Elsevier}},
  series       = {{Physica B: Condensed Matter}},
  title        = {{Characterization of defect microstructure in MgRE (RE=Ce, Nd) alloys after processing by high-pressure torsion using positron annihilation spectroscopy and a high resolution X-ray diffraction}},
  url          = {{http://dx.doi.org/10.1016/j.physb.2023.414963}},
  doi          = {{10.1016/j.physb.2023.414963}},
  volume       = {{663}},
  year         = {{2023}},
}