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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., Huang, Y., Langdon, T. G. and Bradai, D., 2023. 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. Physica B: Condensed Matter. (In Press)

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DOI: 10.1016/j.physb.2023.414963

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 (DBVEPAS). 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).

Item Type:Article
ISSN:0921-4526
Uncontrolled Keywords:Mg; Rare earth; HPT; Dislocations; Positron; Spectroscopy
Group:Faculty of Science & Technology
ID Code:38539
Deposited By: Symplectic RT2
Deposited On:19 May 2023 15:44
Last Modified:19 May 2024 01:08

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