Heterogeneous disconnection nucleation mechanisms during grain boundary migration

Combe, Nicolas; Mompiou, Frédéric; Legros, Marc

doi:10.1103/physrevmaterials.3.060601

Cited by 19 publications

(20 citation statements)

References 32 publications

(43 reference statements)

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“…Such gap between disconnection-containing GBs in real materials and those used in atomistic simulations that are often perfect and separating only two grains (bicrystals) may explain why the observed coupling factors (low) differ from the simulated ones (high). In fact, atomistic simulations of real GBs are only beginning, addressing the possible influence of defects present prior to deformation such as vacancies [78] or immobile disconnections [79]. A second reason for the current mismatch between the observed and simulated coupling factors may be the complex stress tensor acting locally on real GBs in small-grained metals whereas atomistic simulations involve perfectly defined and often homogenous stress states [80].…”

Section: Discussionmentioning

confidence: 99%

Shear-coupled migration of grain boundaries: the key missing link in the mechanical behavior of small-grained metals?

Gautier¹,

Rajabzadeh²,

Larranaga³

et al. 2021

Comptes Rendus. Physique

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Section: Discussionmentioning

confidence: 99%

Shear-coupled migration of grain boundaries: the key missing link in the mechanical behavior of small-grained metals?

Gautier¹,

Rajabzadeh²,

Larranaga³

et al. 2021

Comptes Rendus. Physique

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“…As in clinopyroxene, the nature and abundance of atomic impurities in olivine (e.g., Ni, Cr, Ti) are commonly used as petrogenetic indicators, specifically targeting deep crustal and mantle processes such as partial melting or metasomatism (e.g., Ringwood, 1955a, b;O'Reilly et al, 1997;De Hoog et al, 2010;Foley et al, 2013;Sanfilippo et al, 2017;Neave et al, 2018). Atomic impurities are also used as proxies for equilibrium temperature (Ca in olivine and co-existing orthopyroxene) and pressure (Al in olivine; e.g., Brey and Kohler, 1990;Witt-Eickschen and O'Neill, 2005;Coogan et al, 2014;D'Souza et al, 2020;Bussweiler et al, 2017). Thanks to recent technical advances, we can now measure a broad array of atomic impurities in olivine, from heavy (e.g., Th, U, at concentrations > 1 ppb) to light (e.g., Li) elements, by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS; e.g., Tollan et al, 2018;Bussweiler et al, 2019;Batanova et al, 2019;Demouchy and Alard, 2021).…”

Section: Extrinsic Point Defectsmentioning

confidence: 99%

Defects in olivine

Demouchy¹

2021

Eur. J. Mineral.

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Abstract. Olivine, a ferromagnesian orthosilicate, is the most abundant mineral in Earth's upper mantle and is stable down to the olivine–wadsleyite phase transition, which defines the 410 km depth mantle transition zone. Olivine also occurs in crustal environments in metamorphic and hydrothermal rocks and is expected to be the major mineral constituent of the Martian and Venusian mantles. The olivine atomic structure is also used in materials science to manufacture lithium batteries. Like any other crystalline solid, including minerals, olivine never occurs with a perfect crystalline structure: defects in various dimensions are ubiquitous, from point, line, and planar defects to three-dimensional (3-D) inclusions. In this contribution, I review the current state of the art of defects in olivine and several implications for key processes occurring in Earth's mantle. Intrinsic and extrinsic point defects are detailed, exemplifying the astonishing diversity of atomic impurities in mantle-derived olivine. Linear defects, one of the key defect types responsible for ductile deformation in crystalline solids, are examined in light of recent progress in 3-D transmission electron microscopy, which has revealed an important diversity of dislocation slip systems. I summarize the principal characteristics of interface defects in olivine: the free surface, grain and interface boundaries, and internal planar defects. As the least-studied defects to date, interface defects represent an important challenge for future studies and are the main application of numerical simulation methods in materials science. I provide an overview of melt, fluid, and mineral inclusions, which are widely studied in volcanology and igneous petrology. Special attention is given to new crystalline defects that act as deformation agents: disclinations (rotational defects) and the potential occurrence of disconnections in olivine, both of which are expected to occur along or near grain boundaries. Finally, I detail outstanding questions and research directions that will further our understanding of the crystalline specificities and paradoxes of olivine and olivine-rich rocks and ultimately their implications for the dynamics of Earth's upper mantle.

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“…This twin thickening controlled by twin dislocation sources resulting from slip dissociations at twin interfaces is referred as slip-assisted [35]. Sources of disconnections in {1012} twin boundary [29,[36][37][38], in {112} twin boundary [39] and in {410} grain boundary [40] are examples for hcp, bcc and fcc crystals respectively. If the twin dislocation source does not require previous slip activity, the source is slip dislocation-independent [35].…”

Section: Sources Of Disconnectionsmentioning

confidence: 99%

Review of Non-Classical Features of Deformation Twinning in hcp Metals and Their Description by Disconnection Mechanisms

Ostapovets

Serra

2020

Metals

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The study of deformation twinning has long history. However new, sometimes surprising, findings have shown that the phenomenon of deformation twinning still is not completely understood. During recent years, some debates are taking place in the scientific literature concerning deformation twinning mechanisms in metals with hcp structure. These debates deal with the importance of special twin boundary dislocations named disconnections, growth and nucleation of twins, non-Schmid behavior of twinning, difference of deformation produced by twins from simple shear. They invoked new propositions for atomistic mechanisms of deformation twinning. The purpose of this review is to compare the classical theories of interfacial defects with the new findings and prove that many of these findings can be understood in terms of these well-established theories. The main attention is paid to summarizing the explanations of different phenomena in terms of disconnection mechanisms in order to show that there is no contradiction between these mechanisms and the new findings.

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Heterogeneous disconnection nucleation mechanisms during grain boundary migration

Cited by 19 publications

References 32 publications

Shear-coupled migration of grain boundaries: the key missing link in the mechanical behavior of small-grained metals?

Shear-coupled migration of grain boundaries: the key missing link in the mechanical behavior of small-grained metals?

Defects in olivine

Review of Non-Classical Features of Deformation Twinning in hcp Metals and Their Description by Disconnection Mechanisms

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