TEM-in situ deformation of beryllium single crystals—a new explanation for the anomalous temperature dependence of the critical resolved shear stress for prismatic slip

Beuers, J.; Jönsson, Sigurd; Petzow, G.

doi:10.1016/0001-6160(87)90075-7

Cited by 27 publications

(7 citation statements)

References 12 publications

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“…Beryllium deforms by dislocation slip on the basal and prismatic planes [16,17], but prismatic glide exhibits a strong anomalous increase of the yield stress with temperature close to the room temperature, which can be ascribed to strong friction stresses [18,19]. Twinning through gliding dislocations mechanisms have been proposed early in hcp metals [20][21][22][23].…”

Section: Introductionmentioning

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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Section: Introductionmentioning

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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“…Models in which hardening is a consequence of the thermal activation of glide in the crossslip planes also belong to this category. This is the case for beryllium, according to Beuers, Jonsson and Petzow (1987), and for titanium, according to Naka (1983) (there is no stress anomaly in this case but only a flat part of the stresstemperature curve). For the former, hardening is assumed to arise through the formation of 'salient points' on dislocations, namely abrupt changes in direction and slip plane after cross-slip.…”

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confidence: 81%

Prismatic slip in beryllium

Couret

Caillard

1989

Philosophical Magazine A

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“…In all cases, basal slip is not geometrically favored although it is the easiest slip system. 16 In bulk samples, because the CRSS of basal slip is about 8 times smaller than for prismatic slip at room temperature, 17 slip systems with low Schmid factor can still be activated. This may explain the presence of hai dislocation moving in the basal plane parallel to the wire axis (d 2 in Fig.…”

Section: Dislocation Plasticitymentioning

confidence: 99%

“…14,15 Prismatic glide exhibits a strong anomalous increase of the yield stress with temperature close to room temperature, which can be ascribed to strong friction stresses. 16,17 In addition to dislocation slip, 10 12 f g twinning is also frequently activated. In a previous work, we have shown that a twin boundary can propagate under stress by the nucleation of twinning dislocations presumably from the surface.…”

Section: Introductionmentioning

confidence: 99%