Stress Relaxation in Crystals

Dotsenko, V. I.

doi:10.1002/pssb.2220930102

Cited by 158 publications

(76 citation statements)

References 77 publications

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“…Macroscopically, the activation volume can be measured during a relaxation stress by plotting the variation of the strain rate logarithm versus the stress logarithm according to [12,59]: If we consider that the dislocation density remain constant, the variation of the strain rate is equal to the variation of the dislocation speed. During in-situ experiment, the variation of the dislocation speed with the local stress, measured through the dislocation curvature, can be tentatively extracted leading to the determination of the activation volume.…”

Section: Activation Volume Measurementmentioning

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: Activation Volume Measurementmentioning

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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“…From these curves, the athermal and thermally activated components of stress were estimated using Li's method. [27,28] In the method, the stresses at three points r 1 , r 2 , and r 3 , are determined on the relaxation curve, where the stress reduction rate satisfies the condition of _…”

Section: Resultsmentioning

confidence: 99%

Solid Solution Strengthening for Mg-3.0 Mass Pct (2.71 At. Pct)Al and Mg-0.06 Mass Pct (0.036 At. Pct)Ca Alloys

Chino

Kado

Ueda

et al. 2010

Metall Mater Trans A

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Tensile tests were carried out at 123 K to 373 K (-150°C to 100°C) on pure Mg, Mg-3.0 mass pct (2.71 at. pct) Al alloy, and Mg-0.06 mass pct (0.036 at. pct) Ca alloy. Little decrease occurred in the yield stress of the pure Mg and the Mg-Ca alloy with increasing temperature from 223 K to 373 K (-50°C to 100°C). For the Mg-Al alloy, however, its yield stress decreased with increasing temperature from 223 K to 373 K (-50°C to 100°C). Analyses based on the existing solid-solution strengthening theories, focusing on the athermal component of stress, revealed that the dominant strengthening mechanism is the shear modulus effect for the Mg-Ca alloy and the chemical interaction for the Mg-Al alloy. It is suggested that the shear modulus effect is dominant at a low concentration and the chemical interaction is dominant at a high concentration for Mg alloys.

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“…I n many experiments the stress relaxation phenomena [6] are attributed to the nonlinear behaviour of a medium affected by external stress as follows : The linear response may also be investigated by use of (58), in which oij describes the stress fluctuations. Indeed, a t high temperatures the stress fluctuations increase.…”

Section: Non-debye Linear Response and Stress Relaxation Experimentsmentioning

confidence: 99%