Characterization of the cell block structure and disclination configurations in plastically deformed metals by electron diffraction

Motylenko, Mykhaylo; Klemm, Volker; Klimanek, P.; Pavlovitch, T.; Straube, H.

doi:10.1016/j.jallcom.2003.10.085

Cited by 18 publications

(9 citation statements)

References 5 publications

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“…Taking such n-pole configurations into account, the estimated critical strength may further decrease. With this note, the above estimates are indeed consistent with the results of experimental measurements (Motylenko et al, 2004), which show the Chapter 5…”

Section: Discussionsupporting

confidence: 89%

“…Furthermore, Rybin and co-workers from their extensive experimental and theoretical studies of substructure evolution during large plastic deformation concluded that disclinations are accumulated in triple junctions of grains due to their strain incompatibilities (Rybin, 1986;Rybin et al, 1993;Zisman and Rybin, 1996). In fact, junction disclinations due to large plastic deformation have been observed directly by TEM (Motylenko et al, 2004). These triple junction disclinations can have strengths up to 3° (Rybin, 1986;Motylenko et al, 2004).…”

Section: Formation Mechanisms Of Disclinations In Solidsmentioning

confidence: 99%

“…In fact, junction disclinations due to large plastic deformation have been observed directly by TEM (Motylenko et al, 2004). These triple junction disclinations can have strengths up to 3° (Rybin, 1986;Motylenko et al, 2004).…”

Section: Formation Mechanisms Of Disclinations In Solidsmentioning

confidence: 99%

“…The studies of substructure evolution during large plastic deformation showed that disclinations are accumulated in triple junctions of grains due to their strain incompatibilities (Rybin, 1986;Rybin et al, 1993;Zisman and Rybin, 1996). These junction disclinations can have strengths up to 3° (Rybin, 1986;Motylenko et al, 2004) and have been observed by TEM (Motylenko et al, 2004). Therefore, triple junction disclinations can constitute an essential element of the structure of nanocrystalline materials produced by severe plastic deformation and as such significantly influence their structural stability as well as mechanical and physical properties (Valiev et al, 2000;Nazarov and Mulyukov, 2003).…”

Section: Introductionmentioning

confidence: 99%

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Mechanics of disclinated interfaces and cracks in polycrystalline an nanocrystalline materials

Zhou¹

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Gain boundaries (GBs) and crystal lattices in nanocrystalline materials contain defects, which may grow and induce failure of the materials. A critical issue for developing nanocrystalline materials is thus the modeling of material microstructures and constituent defects as well as the simulation of their behavior under load. In particular, the disclination defect, commonly found in nanocrystalline materials, is investigated in this research. The research focuses on the description of material interfaces by a disclination dipole wall and on the investigation of cracks initiating from disclinations. First, the mechanics model of an interfacial wedge disclination dipole wall in a hexagonal bicrystal is established by the method of image dislocations. The exact closed-form solutions for the elastic stress and strain energy density are shown to be of the form of the logarithm of hyperbolic and trigonometric functions of complex parameters. The results show that the stress, strain energy density and strain energy all depend significantly on the orientational and material inhomogeneities. Second, the disclination-structural unit model in conjunction with the mechanics model of the dipole wall is developed for the physical description of GBs in hexagonal bicrystals. For [1100] symmetrical tilt GBs in cobalt and titanium, it is shown that the GB stress field and energy depend strongly on the misorientation. In particular, the GB stress field is more localized in high-angle boundaries than in small-angle boundaries and severe distortion of the stress field results from even a small inhomogeneity. The energy-misorientation curve is characterized by cusps associated with favored 1

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Section: Discussionsupporting

confidence: 89%

Section: Formation Mechanisms Of Disclinations In Solidsmentioning

confidence: 99%

Section: Formation Mechanisms Of Disclinations In Solidsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Mechanics of disclinated interfaces and cracks in polycrystalline an nanocrystalline materials

Zhou¹

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“…Such disclinations play a key role in grain subdivision during deformation [12], and can be inherited by bulk nanostructured materials produced by severe plastic deformation [6 -8]. Indeed, disclinations have been observed directly via electron microscopy in metals such as copper and titanium subjected to severe plastic deformation [13] and in nanostructured iron produced by high-energy ball milling [14].…”

mentioning

confidence: 99%

Competing Relaxation Mechanisms in a Disclinated Nanowire: Temperature and Size Effects

Zhou

Назаров

2007

Phys. Rev. Lett.

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This Letter reports a molecular dynamics study of the temperature and size dependence of disclination relaxation in a bicrystalline titanium nanowire. The simulations show that an unstable disclination may relax via crack nucleation and/or structural transformation. The critical disclination strength to nucleate a crack decreases with the nanowire diameter at 0 K, but an inverse relation may exist at higher temperatures. Similar relaxation mechanisms are operative in other hcp materials. The results suggest that grain boundaries in nanostructured materials can be disordered through disclinations which relax via amorphization.

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Bulk Nanostructured Materials by SPD Processing: Techniques, Microstructures and Properties

Valiev

Назаров

2009

Bulk Nanostructured Materials

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Characterization of the cell block structure and disclination configurations in plastically deformed metals by electron diffraction

Cited by 18 publications

References 5 publications

Mechanics of disclinated interfaces and cracks in polycrystalline an nanocrystalline materials

Mechanics of disclinated interfaces and cracks in polycrystalline an nanocrystalline materials

Competing Relaxation Mechanisms in a Disclinated Nanowire: Temperature and Size Effects

Bulk Nanostructured Materials by SPD Processing: Techniques, Microstructures and Properties

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