Dislocation and disclination densities in experimentally deformed polycrystalline olivine

Demouchy, Sylvie; Thieme, Manuel; Barou, Fabrice; Beausir, Benoit; Taupin, Vincent; Cordier, Patrick

Type de document :

Article dans une revue scientifique: Article original

DOI :

10.5194/ejm-35-219-2023

URL permanente :

http://hdl.handle.net/20.500.12210/79414

Titre :

Dislocation and disclination densities in experimentally deformed polycrystalline olivine

Auteur(s) :

Demouchy, Sylvie [Auteur]
Laboratoire Magmas et Volcans [LMV]
Géosciences Montpellier
Thieme, Manuel [Auteur]
Géosciences Montpellier
Barou, Fabrice [Auteur]
Géosciences Montpellier
Beausir, Benoit [Auteur]
Laboratoire d'Etude des Microstructures et de Mécanique des Matériaux [LEM3]
Taupin, Vincent [Auteur]
Laboratoire d'Etude des Microstructures et de Mécanique des Matériaux [LEM3]
Cordier, Patrick [Auteur]

Unité Matériaux et Transformations (UMET) - UMR 8207

Titre de la revue :

European Journal of Mineralogy

Nom court de la revue :

Eur. J. Mineral.

Numéro :

Pagination :

219-242

Éditeur :

Copernicus GmbH

Date de publication :

2023-03-31

ISSN :

1617-4011

Discipline(s) HAL :

Physique [physics]/Matière Condensée [cond-mat]/Science des matériaux [cond-mat.mtrl-sci]

Résumé en anglais : [en]

Abstract. We report a comprehensive data set characterizing and quantifying the geometrically necessary dislocation (GND) density in the crystallographic frame (ραc) and disclination density (ρθ) in fine-grained ...
Lire la suite >Abstract. We report a comprehensive data set characterizing and quantifying the geometrically necessary dislocation (GND) density in the crystallographic frame (ραc) and disclination density (ρθ) in fine-grained polycrystalline olivine deformed in uniaxial compression or torsion, at 1000 and 1200 ∘C, under a confining pressure of 300 MPa. Finite strains range from 0.11 up to 8.6 %, and stresses reach up to 1073 MPa. The data set is a selection of 19 electron backscatter diffraction maps acquired with conventional angular resolution (0.5∘) but at high spatial resolution (step size ranging between 0.05 and 0.1 µm). Thanks to analytical improvement for data acquisition and treatment, notably with the use of ATEX (Analysis Tools for Electron and X-ray diffraction) software, we report the spatial distribution of both GND and disclination densities. Areas with the highest GND densities define sub-grain boundaries. The type of GND densities involved also indicates that most olivine sub-grain boundaries have a mixed character. Moreover, the strategy for visualization also permits identifying minor GND that is not well organized as sub-grain boundaries yet. A low-temperature and high-stress sample displays a higher but less organized GND density than in a sample deformed at high temperature for a similar finite strain, grain size, and identical strain rate, confirming the action of dislocation creep in these samples, even for micrometric grains (2 µm). Furthermore, disclination dipoles along grain boundaries are identified in every undeformed and deformed electron backscatter diffraction (EBSD) map, mostly at the junction of a grain boundary with a sub-grain but also along sub-grain boundaries and at sub-grain boundary tips. Nevertheless, for the range of experimental parameters investigated, there is no notable correlation of the disclination density with stress, strain, or temperature. However, a broad positive correlation between average disclination density and average GND density per grain is found, confirming their similar role as defects producing intragranular misorientation. Furthermore, a broad negative correlation between the disclination density and the grain size or perimeter is found, providing a first rule of thumb on the distribution of disclinations. Field dislocation and disclination mechanics (FDDM) of the elastic fields due to experimentally measured dislocations and disclinations (e.g., strains/rotations and stresses) provides further evidence of the interplay between both types of defects. At last, our results also support that disclinations act as a plastic deformation mechanism, by allowing rotation of a very small crystal volume.Lire moins >

Langue :

Anglais

Comité de lecture :

Oui

Audience :

Internationale

Vulgarisation :

Non

Projet Européen :

Rheology of Earth materials: closing the gap between TIMEscales in the laboratory and in the MANtle
Complex RhEologies in Earth dynamics and industrial Processes

Établissement(s) :

Université de Lille
CNRS
INRAE
ENSCL

Collections :

Unité Matériaux et Transformations (UMET) - UMR 8207

Équipe(s) de recherche :

Plasticité

Date de dépôt :

2023-04-01T08:38:38Z
2023-04-03T07:40:26Z
2023-04-03T07:56:37Z

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Demouchy-et-al(2023)DisclinationsOlivine.pdf
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Ce document est diffusé sous licence Attribution 3.0 United States

Historique des modifications

Numéro de version	Lien	Date de modification
3	20.500.12210/79414*	2023-04-03T07:50:28Z
2	20.500.12210/79414.2	2023-04-03T07:24:33Z
1	20.500.12210/79414.1	2023-04-01T08:38:38Z

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