Achieving the ideal strength in annealed molybdenum nanopillars

Lowry, M. B.; Kiener, Daniel; LeBlanc, M.M.; Chisholm, Claire; Florando, J.N.; Morris, James R.; Minor, Andrew M.

doi:10.1016/j.actamat.2010.05.052

Cited by 111 publications

(79 citation statements)

References 29 publications

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“…2d,e) and those in previous works 4,12 may result from the onset of the dislocation self-multiplication as described in ref 5. However, it is worth noting that the predicted critical stress in ref 5.…”

Section: Mechanical Annealing In Mosupporting

confidence: 70%

“…2d) after mechanical annealing looks rather like the pristine Mo achieved by high-temperature formation or annealing 4,12 , in the sense of lacking 'obvious' dislocation lines ('obvious' defined here by the contour length of a dislocation being a significant fraction of D) or dislocation forest inside. But one cannot tell whether some point defects or tiny point-defect clusters still remain in the cleaned region, as they are beyond the resolution of conventional TEM.…”

Section: Mechanical Annealing In Momentioning

confidence: 99%

“…Particularly interesting are the behaviours of BCC metals, which in bulk form tend to exhibit significant deviations from FCC metals. Molybdenum (Mo) is a representative and widely studied example [3][4][5][6][12][13][14] of such BCC metals.…”

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confidence: 99%

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A new regime for mechanical annealing and strong sample-size strengthening in body centred cubic molybdenum

Huang

Shan

et al. 2011

Nat Commun

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Because of crystal symmetry, body centred cubic (BCC) metals have large differences in lattice friction between screw and edge dislocations, and manifest generally different mechanical behaviours from face centred cubic (FCC) metals. Although mechanical annealing (significant drop in stored dislocation density in response to applied stress) has been observed in FCC metals, it has not been observed in BCC metals so far. Here we show that significant mechanical annealing does occur in BCC mo pillars, when their diameters decrease to hundreds of nanometers. In addition, there exists a critical diameter for focused ion beam milled pillars, below which the strengthening exponent increases dramatically, from ~0.3 to ~1. Thus, a new regime of size effects in BCC metals is discovered that converges to that of FCC metals, revealing deep connection in the dislocation dynamics of the two systems.

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Section: Mechanical Annealing In Mosupporting

confidence: 70%

Section: Mechanical Annealing In Momentioning

confidence: 99%

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A new regime for mechanical annealing and strong sample-size strengthening in body centred cubic molybdenum

Huang

Shan

et al. 2011

Nat Commun

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“…This fabrication technique has limitations in that the smallest pillar sizes ;100 nm are extremely cumbersome to produce and often suffer from FIB damage and substantial vertical taper. 38,39 Some of the alternative fabrication routes do not suffer from these limitations. For example, two different sets of single crystalline copper pillars have been produced without the use of FIB, 26,[30][31][32] creating nearly taper-free samples with diameters as small as 75 nm.…”

Section: Methodsmentioning

confidence: 99%

Heterogeneous dislocation nucleation from surfaces and interfaces as governing plasticity mechanism in nanoscale metals

Jennings

Greer

2011

J. Mater. Res.

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We report the results of constant strain rate experiments on electroplated, single crystalline copper pillars with diameters between 75 and 525 nm. At slow strain rates, 10 À3 s À1, pillar diameters with 150 nm and above show a size-dependent strength similar to previous reports. Below 150 nm, we find that the size effect vanishes as the strength transitions to a relatively size-independent regime. Strain rate sensitivity and activation volume are determined from uniaxial compression tests at different strain rates and corroborate a deformation mechanism change. These results are discussed in the framework of recent in situ transmission electron microscopy experiments observing two distinct deformation mechanisms in pillars and thin films on flexible substrates: partial dislocation nucleation from stress concentrations in smaller structures and single arm source operation in larger samples. Models attempting to explain these different size-dependent regimes are discussed in relation to these experiments and existing literature revealing further insights into the likely small-scale deformation mechanisms.

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“…В микрокристаллах, выращенных из газовой фазы, отсутствуют объемные и поверхностные дефекты, в то время как на боковой поверхности нанокристаллов, вырезанных ионным пучком, могут присутствовать кон-центраторы напряжений в виде ступенек, а в приповерх-ностном слое -радиационные дефекты (вакансионные петли и петли внедрения). В процессе деформации петли превращаются в скользящие дислокации и снижают тем самым прочность кристалла [11].…”

Section: Introductionunclassified

Размерные Эффекты При Ударном Пластическом Сжатии Наноразмерных Кристаллов

Малыгин¹,

Клявин²

2017

Физика Твердого Тела

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В рамках дислокационно-кинетического подхода, основанного на уравнениях и соотношениях кинетики дислокаций, впервые сделан теоретический анализ размерных эффектов при ударно-пластическом сжатии наноразмерных кристаллов. Получены количественные соотношения для зависимости предела текучести кристаллов τy от размера их поперечного сечения D и скорости ударной деформацииε, τy ∼ε 2/3 D. Указанный вид зависимости имеет место при релаксации упругих напряжений в результате эмиссии дислокаций из однополюсных источников Франка−Рида вблизи поверхности кристалла.

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Achieving the ideal strength in annealed molybdenum nanopillars

Cited by 111 publications

References 29 publications

A new regime for mechanical annealing and strong sample-size strengthening in body centred cubic molybdenum

A new regime for mechanical annealing and strong sample-size strengthening in body centred cubic molybdenum

Heterogeneous dislocation nucleation from surfaces and interfaces as governing plasticity mechanism in nanoscale metals

Размерные Эффекты При Ударном Пластическом Сжатии Наноразмерных Кристаллов

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