Hybrid quantum/classical study of hydrogen-decorated screw dislocations in tungsten: Ultrafast pipe diffusion, core reconstruction, and effects on glide mechanism

A model for the nucleation and growth processes of Sn whisker is offered. High density of localized screw dislocations by deformation form the dense spiral steps of atomic scale on Sn surface. The spiral steps would induce the nucleation of Sn whisker. Edge dislocations localized at the same region where the dense screw dislocations exist supply Sn atoms to Sn whisker through pipe diffusion. Both screw and edge dislocations would bend along almost one direction, namely, to relax the external shear stress. The image force also helps to bend the dislocations perpendicular to the whisker side-surface. The bending of dislocations at root of whisker leads the bend of whisker. The pipe diffusion of Sn atoms through edge dislocations from bulk Sn toward whisker is suppressed at the bent part of edge dislocation, resulting in release of Sn atoms inside whisker and leading to the growth of whisker near its root.

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Formation of Whisker in Pure Sn under Tensile Stress and a Method of its Suppression

Materials Science Forum ◽

10.4028/www.scientific.net/msf.706-709.751 ◽

2012 ◽

Vol 706-709 ◽

pp. 751-756 ◽

Cited By ~ 1

Author(s):

Kiyomichi Nakai ◽

Tatsuaki Sakamoto ◽

Takeaki Miyamoto ◽

Sengo Kobayashi

Keyword(s):

Heat Treatment ◽

Tensile Stress ◽

Slip System ◽

Edge Dislocation ◽

Pipe Diffusion ◽

Sn Whisker ◽

Screw Dislocations ◽

Burgers Vector ◽

Dislocation Behavior ◽

Pure Sn

Effect of dislocation behavior on formation of whisker in pure Sn has been investigated. Slip system in β-Sn was determined; slip plane is , and Burgers vector b is . The magnitude of Burgers vector is larger than the smallest interatomic spacing in β-Sn. This means that there is broad space under the extra half plane of edge dislocation. It sould be noted that pipe diffusion along the edge dislocation is enhanced in β-Sn, resulting in easy supply of Sn atoms at the root of Sn whisker [1, 2]. Si-bearing particles, which precipitate on surface of bulk Sn by heat-treatment in quartz tube, suppress the accumulation of both edge and screw dislocations to same area. It is greatly effective for the suppression of the nucleation of Sn whisker.

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In situ Tensile Experiments at Low Temperatures on Niobium Single Crystals by H.V.E.M.

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100113913 ◽

1975 ◽

Vol 33 ◽

pp. 58-59

Author(s):

F. H. Louchet ◽

L. P. Kubin

Keyword(s):

Electron Microscope ◽

Transition Temperature ◽

Low Temperature ◽

Slip System ◽

Low Temperatures ◽

Tensile Axis ◽

Image Intensifier ◽

Screw Dislocations ◽

Source Operation

Experiments have been carried out on the 3 MeV electron microscope in Toulouse. The low temperature straining holder has been previously described Images given by an image intensifier are recorded on magnetic tape.The microtensile niobium samples are cut in a plane with the two operative slip directions [111] and lying in the foil plane. The tensile axis is near [011].Our results concern:- The transition temperature of niobium near 220 K: at this temperature and below an increasing difference appears between the mobilities of the screw and edge portions of dislocations loops. Source operation and interactions between screw dislocations of different slip system have been recorded.

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Observation of dislocations in dynamically loaded Cu-SiO2

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100143705 ◽

1986 ◽

Vol 44 ◽

pp. 424-425

Author(s):

D. S. Pritchard

Keyword(s):

Electron Microscope ◽

Strain Rate ◽

Single Crystal ◽

Transmission Electron Microscope ◽

Volume Fraction ◽

Screw Dislocations ◽

Spherical Inclusions ◽

Transmission Electron ◽

Crystal Dispersion ◽

Strain Rate Loading

The effect of varying the strain rate loading conditions in compression on a copper single crystal dispersion-hardened with SiO2 particles has been examined. These particles appear as small spherical inclusions in the copper lattice and have a volume fraction of 0.6%. The structure of representative crystals was examined prior to any testing on a transmission electron microscope (TEM) to determine the nature of the dislocations initially present in the tested crystals. Only a few scattered edge and screw dislocations were viewed in those specimens.

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Freeze-fracture TEM of the helical smectic A* phase

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010012179x ◽

1992 ◽

Vol 50 (1) ◽

pp. 278-279

Author(s):

K.J. Ihn ◽

R. Pindak ◽

J. A. N. Zasadzinski

Keyword(s):

Liquid Crystal ◽

Grain Boundary ◽

Grain Boundaries ◽

Freeze Fracture ◽

Smectic Phase ◽

Layer Spacing ◽

Screw Dislocations ◽

Smectic A ◽

Smectic Phases ◽

Discrete Amount

A new liquid crystal (called the smectic-A* phase) that combines cholesteric twist and smectic layering was a surprise as smectic phases preclude twist distortions. However, the twist grain boundary (TGB) model of Renn and Lubensky predicted a defect-mediated smectic phase that incorporates cholesteric twist by a lattice of screw dislocations. The TGB model for the liquid crystal analog of the Abrikosov phase of superconductors consists of regularly spaced grain boundaries of screw dislocations, parallel to each other within the grain boundary, but rotated by a fixed angle with respect to adjacent grain boundaries. The dislocations divide the layers into blocks which rotate by a discrete amount, Δθ, given by the ratio of the layer spacing, d, to the distance between grain boundaries, lb; Δθ ≈ d/lb (Fig. 1).

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A dipole model for the cross-slip of screw dislocations in fcc metals

Philosophical Magazine A ◽

10.1080/01418610210130976 ◽

2002 ◽

Vol 82 (9) ◽

pp. 1691-1711 ◽

Cited By ~ 2

Author(s):

L. M. Brown

Keyword(s):

Cross Slip ◽

Dipole Model ◽

Screw Dislocations ◽

Fcc Metals ◽

The Cross

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Correlation of Phraseological Semantic Fields in Russian Study of Aphorisms

Известия Смоленского государственного университета ◽

10.35785/2072-9464-2020-51-3-60-71 ◽

2020 ◽

pp. 60-71

Author(s):

Anshelika Korolkova

Keyword(s):

Negative Correlation ◽

Semantic Field ◽

Positive Correlation ◽

Classical Study ◽

Semantic Fields ◽

Zero Correlation ◽

Russian Study

The article deals with the interconnection and interdependence of phraseological semantic fields of Russian study of aphorisms in synchronic and in diachronic approaches. The correlation of phraseological semantic fields of Russian study of aphorisms is considered as their interdependence due to various factors (linguistic and extra-linguistic ones). The correlation of the phraseological semantic fields of Russian study of aphorisms is manifested in the existence of many antinomies. The natural linguistic antinomies of life / death / immortality or war / peace, or good / evil, or friend / enemy, or villainy / nobility are reflected in Russian aphorisms and have entered the corresponding phraseological semantic fields. The corpus of Russian study of aphorisms containsnot only antinomic aphorisms, but also antinomic relations that extend to the level of language and speech. Therefore, in Russian study of aphorisms there are phraseological semantic fields that implement these antinomies. In addition to the antinomic phraseological semantic fields in the corpus of classical Russian study of aphorisms there are other types of correlations. The keywords (concepts) of many phraseological semantic fields are closely thematically connected. When the number of units from one field is changed, the number of units in another phraseological semantic field also changes. Most phraseological semantic fields of Russian study of aphorisms do not show a zero correlation in either synchronic or diachronic approaches. This is due to, first of all, the universality of the aphoristic theme, with all the ideological and thematic uniqueness of the sayings used by Russian writers. However, a few phraseological and semantic fields of aphorisms by Russian writers may show a negative correlation, which is due to the diversity of the thematic groups that comprise them. A positive correlation of phraseological semantic fields, the most significant in the number of their constituent components, shows deep internal linguistic systemic connections in Russian classical study of aphorisms.

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