Dislocation structures and their relationship to strength in deformed nickel microcrystals

Norfleet, David M.; Dimiduk, Dennis M.; Polasik, Steven J.; Uchic, Michael D.; Mills, Michael J.

doi:10.1016/j.actamat.2008.02.046

Cited by 301 publications

(164 citation statements)

References 35 publications

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“…In addition, dislocations are also visible. The dislocation density can be roughly calculated by the line intercept method [44], by drawing five random lines through the TEM images with total length Lr and counting the number of the intersection points N, with the following equation:…”

Section: Uniaxial Tensile Testmentioning

confidence: 99%

Material characterisation and finite element modelling of cyclic plasticity behaviour for 304 stainless steel using a crystal plasticity model

Sun

Becker

2016

International Journal of Mechanical Sciences

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A note on versions:The version presented here may differ from the published version or from the version of record. If you wish to cite this item you are advised to consult the publisher's version. Please see the repository url above for details on accessing the published version and note that access may require a subscription. Abstract: Low cycle fatigue tests were carried out for a 304 stainless steel at room temperature. A series of experimental characterisations, including SEM, TEM, and XRD were conducted on for the 304 stainless steel to facilitate the understanding of the mechanical responses and microstructural behaviour of the material under cyclic loading including nanostructure, crystal structure and the fractured surface. The crystal plasticity finite element method (CPFEM) is a powerful tool for studying the microstructure influence on the cyclic plasticity behaviour. This method was incorporated into the commercially available software ABAQUS by coding a UMAT user subroutine. Based on the results of fatigue tests and material characterisation, the full set of material constants for the crystal plasticity model was determined. The CPFEM framework used in this paper can be used to predict the crack initiation sites based on the local accumulated plastic deformation and local plastic dissipation energy criterion, but with limitation in predicting the crack initiation caused by precipitates.

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Section: Uniaxial Tensile Testmentioning

confidence: 99%

Material characterisation and finite element modelling of cyclic plasticity behaviour for 304 stainless steel using a crystal plasticity model

Sun

Becker

2016

International Journal of Mechanical Sciences

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“…Up to now, different modelling approaches have been proposed to characterise phenomena observed in compression of nano-and micron-sized pillars, such as a source-truncation model [19], a source-exhaustion hardening model [20], multiplication via a single-arm source operation [19,21], a weakest-link theory [22] and a dislocation-starvation/dislocation-nucleation theory [23]. The general premise of these theories is to represent dislocation-source operations in a discrete fashion, where strength of samples is linked to the source lengths.…”

Section: Introductionmentioning

confidence: 99%

Indentation studies in b.c.c. crystals with enhanced model of strain-gradient crystal plasticity

Demiral

Roy

2013

Computational Materials Science

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• This is the author's version of a work that was accepted for publication in the Computational Materials Science. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published at:http://www.sciencedirect.com/science/article/pii/S0927025613004072

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“…So far, FIB-less fabrication methods have only been able to produce features without dislocations, thereby rendering theoretical strengths, regardless of size, not surprising. Pillars fabricated by FIB, in contrast, contain as many as 10 13 dislocations per m 2 [32]. Therefore, in order to understand what drives the size effect, it is imperative to mechanically test pillars produced via FIB-less fabrication methods yet with nonzero dislocation densities.…”

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confidence: 99%

Microstructure versus Size: Mechanical Properties of Electroplated Single Crystalline Cu Nanopillars

2010

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We report results of uniaxial compression experiments on single-crystalline Cu nanopillars with nonzero initial dislocation densities produced without focused ion beam (FIB). Remarkably, we find the same power-law size-driven strengthening as FIB-fabricated face-centered cubic micropillars. TEM analysis reveals that initial dislocation density in our FIB-less pillars and those produced by FIB are on the order of 10 14 m À2 suggesting that mechanical response of nanoscale crystals is a stronger function of initial microstructure than of size regardless of fabrication method.

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Dislocation structures and their relationship to strength in deformed nickel microcrystals

Cited by 301 publications

References 35 publications

Material characterisation and finite element modelling of cyclic plasticity behaviour for 304 stainless steel using a crystal plasticity model

Material characterisation and finite element modelling of cyclic plasticity behaviour for 304 stainless steel using a crystal plasticity model

Indentation studies in b.c.c. crystals with enhanced model of strain-gradient crystal plasticity

Microstructure versus Size: Mechanical Properties of Electroplated Single Crystalline Cu Nanopillars

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