Evolution of microstructure in hcp metals during irradiation

Griffiths, M.

doi:10.1016/0022-3115(93)90085-d

Cited by 95 publications

(53 citation statements)

References 35 publications

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“…Voids could form in almost all materials under irradiation 8,9,[13][14][15][16][17][18][19][20] . They nucleate from the agglomeration of mobile vacancies, and evolve with the absorption and emission of vacancies or self-interstitials at the void surfaces 21 .…”

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confidence: 99%

“…Materials under irradiation of high-energy particles, such as neutrons, ions and electrons, will develop point defects or defect clusters, which may subsequently evolve into microstructural flaws, such as voids, dislocation loops, solute segregation or precipitation 3,[8][9][10][11][12] . Such defects and flaws not only deteriorate the physical properties of irradiated materials, but also cause direct structural failure.…”

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confidence: 99%

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In-situ atomic-scale observation of irradiation-induced void formation

et al. 2013

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The formation of voids in an irradiated material significantly degrades its physical and mechanical properties. Void nucleation and growth involve discrete atomic-scale processes that, unfortunately, are not yet well understood due to the lack of direct experimental examination. Here we report an in-situ atomic-scale observation of the nucleation and growth of voids in hexagonal close-packed magnesium under electron irradiation. The voids are found to first grow into a plate-like shape, followed by a gradual transition to a nearly equiaxial geometry. Using atomistic simulations, we show that the initial growth in length is controlled by slow nucleation kinetics of vacancy layers on basal facets and anisotropic vacancy diffusivity. The subsequent thickness growth is driven by thermodynamics to reduce surface energy. These experiments represent unprecedented resolution and characterization of void nucleation and growth under irradiation, and might help with understanding the irradiation damage of other hexagonal close-packed materials.

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confidence: 99%

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In-situ atomic-scale observation of irradiation-induced void formation

et al. 2013

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“…The blue data points are the MD results, with the open squares representing the result of recovery mechanism and the filled squares representing the climb mechanism. The green line on the left denoted as "MS" represents the result from previous molecular static simulations (2), and the red triangle denoted as "exp." represents the result from experiments (9) as an outcome of dislocation-SIA cluster interactions in hcp Zr.…”

Section: Mechanism Map In Strain Rate and Temperaturementioning

confidence: 99%

“…This is especially important for irradiated materials where a host of nonequilibrium defect structures are produced. They act as obstacles to moving dislocations, alter the mechanical properties, and critically impact the safety and integrity of structural materials in nuclear energy systems (1)(2)(3). Molecular dynamics (MD) methods have proven to be useful in revealing the deformation mechanism with atomic-scale details (4), yet they are limited to a high strain-rate regime, about 10 6 s −1 and above.…”

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confidence: 99%

Mapping strain rate dependence of dislocation-defect interactions by atomistic simulations

Fan¹,

Osetsky

Yip

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

104

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Probing the mechanisms of defect-defect interactions at strain rates lower than 10 6 s −1 is an unresolved challenge to date to molecular dynamics (MD) techniques. Here we propose an original atomistic approach based on transition state theory and the concept of a strain-dependent effective activation barrier that is capable of simulating the kinetics of dislocation-defect interactions at virtually any strain rate, exemplified within 10 −7 to 10 7 s −1 . We apply this approach to the problem of an edge dislocation colliding with a cluster of self-interstitial atoms (SIAs) under shear deformation. Using an activation-relaxation algorithm [Kushima A, et al. (2009) J Chem Phys 130:224504], we uncover a unique strain-ratedependent trigger mechanism that allows the SIA cluster to be absorbed during the process, leading to dislocation climb. Guided by this finding, we determine the activation barrier of the trigger mechanism as a function of shear strain, and use that in a coarsegraining rate equation formulation for constructing a mechanism map in the phase space of strain rate and temperature. Our predictions of a crossover from a defect recovery at the low strainrate regime to defect absorption behavior in the high strain-rate regime are validated against our own independent, direct MD simulations at 10 5 to 10 7 s −1 . Implications of the present approach for probing molecular-level mechanisms in strain-rate regimes previously considered inaccessible to atomistic simulations are discussed.structural materials | mechanical properties | low strain rate atomistic simulation

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“…Таким об-разом, образование вакансионных петель с-типа в базисных плоскостях приводит к ориентацион-но направленному переносу атомов вещества на призматические плоскости и, как следствие, фор-моизменению материала. Сравнение относитель-ных перемещенных объемов исследованных спла-вов позволяет сделать вывод, что сплав Э110 более всего подвержен формоизменению, а сплав Э110м имеет значительную радиационную сопротивляе- [6]. По современным представлениям основным фактором, определяющим стадию ускоренного радиационного роста, является эволюция дисло-кационной структуры.…”

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