Application of disclination concept to solid structures

Романов, А. Е.; Kolesnikova, A. L.

doi:10.1016/j.pmatsci.2009.03.002

Cited by 204 publications

(113 citation statements)

References 89 publications

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“…Closing the gap in the packing of the fcc domains introduces inhomogeneous strain into the system and is equivalent to the introduction of a positive wedge disclination with a power of 7.35º [79,80]. The strong quadratic dependence of the elastic strain energy of a disclination on the size of the crystal precludes the five-fold twinned structures from appearing in bulk crystals and largely limits their habitat to nanoparticles and nanowires with sizes up to several tens of nanometers [79,[80][81][82][83].…”

Section: Structure Of the Nanocrystalline Surface Layermentioning

confidence: 99%

“…The strong quadratic dependence of the elastic strain energy of a disclination on the size of the crystal precludes the five-fold twinned structures from appearing in bulk crystals and largely limits their habitat to nanoparticles and nanowires with sizes up to several tens of nanometers [79,[80][81][82][83]. The pentagonal twinned structures have also been reported for nanocrystalline metals synthesized by severe plastic deformation techniques [84][85][86], where the formation of the fivefold deformation twins is attributed to a sequential twinning occurring under conditions of changing orientation of external stresses [87,88].…”

Section: Structure Of the Nanocrystalline Surface Layermentioning

confidence: 99%

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Generation of subsurface voids and a nanocrystalline surface layer in femtosecond laser irradiation of a single-crystal Ag target

et al. 2015

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Structural transformations in a shallow surface region of a bulk Ag (001) target irradiated by a femtosecond laser pulse are investigated in large-scale atomistic simulations and experiments.The simulations reveal a complex interplay of fast laser melting, rapid resolidification, and the dynamic relaxation of laser-induced stresses that leads to the formation of a sub-surface porous region covered by a nanocrystalline surface layer. The generation of the porous region is consistent with the experimental observation of surface "swelling" occurring at laser fluences below the spallation/ablation threshold and may be related to the incubation effect in multi-pulse laser ablation of metals. The nanocrystalline layer is produced by massive nucleation of crystallites triggered by a deep undercooling of the melted surface region experiencing fast quenching at a rate on the order of 10 11 K/s. The predicted surface structure features random crystallographic orientation of nanograins and a high density of stacking faults, twins, and nanoscale twinned structural elements with five-fold symmetry, which suggests high hardness and possible enhancement of catalytic activity of the surface.

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Section: Structure Of the Nanocrystalline Surface Layermentioning

confidence: 99%

Section: Structure Of the Nanocrystalline Surface Layermentioning

confidence: 99%

Generation of subsurface voids and a nanocrystalline surface layer in femtosecond laser irradiation of a single-crystal Ag target

et al. 2015

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“…1b). The energy E ω À b 1 int 1 is calculated in a standard manner [42,43] as the work done in generating the 7 b 1 dislocation dipole in the stress field created by the disclination dipole AA 0 , which can be expressed as follows after some mathematical treatment:…”

Section: Energy Characteristics Of Dislocation Emission Due To Shearcmentioning

confidence: 99%

Enhancing dislocation emission in nanocrystalline materials through shear-coupled migration of grain boundaries

Soh

2014

Materials Science and Engineering: A

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a b s t r a c tA theoretical model has been developed to illustrate the effect of shear-coupled migration of grain boundaries on dislocation emission in nanocrystalline materials. The energy characteristics and critical shear stress τ c that is required to initiate the emission process were determined. The results obtained show that the dislocation emission can be considerably enhanced as shear-coupled migration was the dominating process; a critical coupling factor that corresponded to the minimum τ c , which led to an optimal dislocation emission, was also discovered. The proposed model has also been quantitatively validated by the existing molecular dynamics simulations.

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“…Согласно [1][2][3][4][5], фрагментация пластически деформи-руемых поликристаллов является следствием зарожде-ния и последующей эволюции стыковых и частичных дисклинаций деформационного происхождения (ДП) -специфических линейных макро-и линейно-планарных мезо-дефектов ротационного типа [6][7][8][9][10][11][12][13][14]. Последова-тельность и иерархическая соподчиненность происходя-щих при этом процессов 1 представляются следующей.…”

Section: Introductionunclassified

Структурные Превращения На Начальных Стадиях Фрагментации Пластически Деформируемых Поликристаллов. Компьютерный Эксперимент

Рыбин¹,

Перевезенцев²,

Свирина³

2017

Журнал Технической Физики

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Представлены результаты компьютерного эксперимента по изучению одновременно на микро-, мезо-и макроуровнях рассмотрения эволюции дислокационной структуры в крупной, примыкающей к одному из стыков, области зерна после его макропластической деформации с постоянной скоростью до величины, соответствующей началу стадии развитой пластической деформации. Проанализирован характер распреде-ления плотности дислокаций и дислокационного заряда, величины и степени неоднородности локальной пластической деформации. Установлено, вследствие каких дислокационных перестроек на стыках и изломах большеугловых границ зерен формируются первые оборванные дислокационные границы -мезодефекты, запускающие процесс фрагментации.

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Application of disclination concept to solid structures

Cited by 204 publications

References 89 publications

Generation of subsurface voids and a nanocrystalline surface layer in femtosecond laser irradiation of a single-crystal Ag target

Generation of subsurface voids and a nanocrystalline surface layer in femtosecond laser irradiation of a single-crystal Ag target

Enhancing dislocation emission in nanocrystalline materials through shear-coupled migration of grain boundaries

Структурные Превращения На Начальных Стадиях Фрагментации Пластически Деформируемых Поликристаллов. Компьютерный Эксперимент

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