Chapter 95 Dislocations in Minerals

Barber, D. J.; Wenk, H. R.; Hirth, Greg; Kohlstedt, D. L.

doi:10.1016/s1572-4859(09)01604-0

Cited by 23 publications

(15 citation statements)

References 338 publications

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“…For micro-pillars of geological calcite after significant plastic deformation, a large number of dislocations were generated, where individual dislocation lines are highly curved without well-defined geometries, a characteristic of dislocations in calcite (Fig. 5a, b) 36 . It has long been known that geological calcite deforms plastically via deformation twinning and slip, particularly at elevated temperatures and confined hydrostatic pressures [37][38][39] .…”

Section: Resultsmentioning

confidence: 99%

Strategies for simultaneous strengthening and toughening via nanoscopic intracrystalline defects in a biogenic ceramic

et al. 2020

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While many organisms synthesize robust skeletal composites consisting of spatially discrete organic and mineral (ceramic) phases, the intrinsic mechanical properties of the mineral phases are poorly understood. Using the shell of the marine bivalve Atrina rigida as a model system, and through a combination of multiscale structural and mechanical characterization in conjunction with theoretical and computational modeling, we uncover the underlying mechanical roles of a ubiquitous structural motif in biogenic calcite, their nanoscopic intracrystalline defects. These nanoscopic defects not only suppress the soft yielding of pure calcite through the classical precipitation strengthening mechanism, but also enhance energy dissipation through controlled nano- and micro-fracture, where the defects’ size, geometry, orientation, and distribution facilitate and guide crack initialization and propagation. These nano- and micro-scale cracks are further confined by larger scale intercrystalline organic interfaces, enabling further improved damage tolerance.

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Section: Resultsmentioning

confidence: 99%

Strategies for simultaneous strengthening and toughening via nanoscopic intracrystalline defects in a biogenic ceramic

et al. 2020

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“…The lattices of minerals contain a variety of defects associated with deviations from a periodic arrangement of atoms. These defects may develop both during crystal growth (Klapper ) and subsequent deformation and recrystallisation (e.g., Barber et al ). They are important because such defects are critical in controlling mineral properties, behaviour, and the mechanisms of intracrystalline element mobility, and there is a clear and important link between incompatible trace element distribution and the formation and evolution of mineral defects (Buseck and Veblen , Argunova et al , Zhang et al , Camacho et al , Zhang and Wright , Wu and Buseck ).…”

Section: Geoscience Applicationsmentioning

confidence: 99%

Atom Probe Tomography: Development and Application to the Geosciences

Reddy

Saxey

Rickard

et al. 2020

Geostandard Geoanalytic Res

102

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Atom probe tomography (APT) is an analytical technique that provides quantitative three‐dimensional elemental and isotopic analyses at sub‐nanometre resolution across the whole periodic table. Although developed and mostly used in the materials science and semiconductor fields, recent years have seen increasing development and application in the geoscience and planetary science disciplines. Atom probe studies demonstrate compositional complexity at the nanoscale and provide fundamental new insights into the atom‐scale mechanisms taking place in minerals over geological time. Here, we provide an overview of APT, including the historical development and technical aspects of the instrumentation, and the fundamentals of data acquisition, data processing and data reconstruction. We also review previous studies and highlight the potential future applications of nanoscale geochemical studies of natural materials.

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“…which, if the yield functions are coupled, provides the following evolution laws for the internal variables: [Barber et al, 2010] with permission from Elsevier. Bottom photograph: micrograph courtesy of Zsolt Schléder and Janos Urai: domal salt from the Klodawa diapir in Poland [Schléder et al, 2007, Urai et al, 1987 in which the Lagrangian multipliers are obtained by using the consistency conditions:…”

Section: Healing Mechanicsmentioning

confidence: 99%

Micro-macro mechanics of damage and healing in rocks

Arson¹

2020

Open Geomechanics

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This paper presents the state of the art of the theory of rock damage and healing mechanics, with a particular emphasis on the strategies available to relate the micro-scale of crystals, cracks and pores to the scale of a Representative Elementary Volume (REV). We focus on mechanical degradation and recovery of stiffness and strength. Damage and healing models formulated in the author's group are used as examples to illustrate and compare the reviewed micromacro approaches, which include fabric enrichment, micromechanical formulations and homogenization schemes. This manuscript was written for doctoral students or researchers relatively new to the field of damage mechanics of geomaterials. Equations are provided to explain how to formulate a thermodynamically consistent model from scratch. Reviewing damage and healing modeling strategies led to the following conclusions: (i) The framework of hyperplasticity, which does not require any postulate on the existence or uniqueness of yield functions and which automatically ensures thermodynamic consistency, was never applied to Continuum Damage Mechanics (CDM). There may be an avenue to improve state-of-the-art damage and healing models in a similar framework of "hyperdamage mechanics". (ii) In damage softening models, the mesh dependence of the width of the damage localization zone is currently alleviated by non-local regularization. Perhaps the next step is to couple micro-macro damage and healing models at the REV scale to discrete fracture mechanics at a larger scale to understand how damage and healing localization occurs. (iii) There may be an opportunity to use fabric-enriched models to capture the effect of microstructure organization on both mechanical properties and permeability. (iv) Coupling chemomechanical damage and healing processes across the scales would be useful to model the competition between damagre and healing whenever both can occur at the same temperature and pressure conditions. (v) Many challenges still exist to implement healing models in the Finite Element Method, especially in regards to the mapping of net damage.

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Chapter 95 Dislocations in Minerals

Cited by 23 publications

References 338 publications

Strategies for simultaneous strengthening and toughening via nanoscopic intracrystalline defects in a biogenic ceramic

Strategies for simultaneous strengthening and toughening via nanoscopic intracrystalline defects in a biogenic ceramic

Atom Probe Tomography: Development and Application to the Geosciences

Micro-macro mechanics of damage and healing in rocks

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