Source-based strengthening of sub-micrometer Al fibers

Mompiou, Frédéric; Legros, Marc; Sedlmayr, Andreas; Gianola, Daniel S.; Caillard, D.; Kraft, O.

doi:10.1016/j.actamat.2011.11.005

Cited by 79 publications

(48 citation statements)

References 29 publications

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“…Keiner and Minor [34,35] have observed in their small copper pillars the operation and loss of dislocation sources. While this is in agreement with the simulations performed here, we note the work of Mompiou et al [48] shows the stable operation of a single arm source in their aluminum fibers. This appears, at first glance, to contradict the simulation results reported here.…”

Section: The Stability Of Dislocation Pinning Pointssupporting

confidence: 94%

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The fundamentals of plastic deformation : several case studies of plasticity in confined volumes.

Weinberger

2012

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Plasticity in small volumes is significantly different than in large, bulk-like specimens. The strength of materials in the micron and sub-micron regime depends not only on the microstructure but also on the size of the material. Given that a number of important mechanical processes occur at these length scales, it is important to build a comprehensive understanding of these materials and processes. This work examines several different processes in small volumes. The motion of dislocations in the drag regime are examined as a function of material volume which exhibits higher drag than in the bulk. The stability of single arm sources are also investigated using molecular dynamics. Finally, dislocation nucleation from the free surface is investigated using both atomistic as well as continuum models. These results provide a better understanding of plastic processes in confined volumes.3 Acknowledgment

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Section: The Stability Of Dislocation Pinning Pointssupporting

confidence: 94%

“…This appears, at first glance, to contradict the simulation results reported here. However, the work of Mompiou et al [48] does not report the exact nature of the pinning point in their experiments. Rather than considering the experiments and theory at odds with one another, we can reconcile the two results.…”

Section: The Stability Of Dislocation Pinning Pointsmentioning

confidence: 92%

The fundamentals of plastic deformation : several case studies of plasticity in confined volumes.

Weinberger

2012

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“…Fibers which are detached at one end can be bent, and a high dislocation density can be observed in the bent area. This indicates that plastic deformation until fracture has occurred prior the experiments in a very limited area, similarly as observed in aluminium fibers [47]. More details on plastic deformation by dislocation slip will be given in a forthcoming article.…”

Section: Resultsmentioning

confidence: 52%

“…Freestanding beryllium fibers where obtained from a directionally Al-2.4 at.%Be eutectic alloy with the same approach described in [47]. 3 by 1mm samples were first cut in a bulk ingot by an electrodischarging machine with the long direction parallel to the fiber length.…”

Section: Methodsmentioning

confidence: 99%

In situ TEM study of twin boundary migration in sub-micron Be fibers

Mompiou

Legros

Ensslen³

et al. 2015

Acta Materialia

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Deformation twinning in hexagonal crystals is often considered as a way to palliate the lack of independent slip systems. This mechanism might be either exacerbated or shut down in small-scale crystals whose mechanical behavior can significantly deviate from bulk materials. Here, we show that sub-micron beryllium fibers initially free of dislocation and tensile tested in-situ in a transmission electron microscope (TEM) deform by a {1012} 1011 twin thickening. The propagation speed of the twin boundary seems to be entirely controlled by the nucleation of twinning dislocations directly from the surface. The shear produced is in agreement with the repeated lateral motion of twinning dislocations. We demonstrate that the activation volume (V) associated with the twin boundary propagation can be retrieved from the measure of the twin boundary speed as the stress decreases as in a classical relaxation mechanical test. The value of V ≈ 8.3 ± 3.3 × 10 −29 m 3 is comparable to the value expected from surface nucleation. This text is a revised version of the article published in Acta Materialia, 96 (2015) 57-65

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“…This steady-state stage indicates that the dislocation multiplication-rate and the escape-rate are equal. The dislocation multiplication is accomplished though the continuous activation of single-ended dislocation sources (see supplementary movie #1) similar to observations from in situ TEM [28] and discrete dislocation dynamics simulations. [29] For 50 nm simulation cells with initial dislocation density ρ 0 = 3 × 10 15 (not shown here), the dislocation density is observed to decrease rapidly until all preexisting dislocations escape the crystals (i.e.…”

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confidence: 61%