Burgers dislocations. Medical search. Frequent questions

In materials science, the Burgers vector, named after Dutch physicist Jan Burgers, is a vector, often denoted as b, that represents the magnitude and direction of the lattice distortion resulting from a dislocation in a crystal lattice. (wikipedia.org)
What was once a rectangle before the dislocation was introduced is now an open geometric figure, whose opening defines the direction and magnitude of the Burgers vector. (wikipedia.org)
Specifically, the breadth of the opening defines the magnitude of the Burgers vector, and, when a set of fixed coordinates is introduced, an angle between the termini of the dislocated rectangle's length line segment and width line segment may be specified. (wikipedia.org)
When calculating the Burgers vector practically, one may draw a rectangular counterclockwise circuit (Burgers circuit) from a starting point to enclose the dislocation (see the picture above). (wikipedia.org)
The Burgers vector will be the vector to complete the circuit, i.e., from the end to the start of the circuit. (wikipedia.org)
The direction of the vector depends on the plane of dislocation, which is usually on one of the closest-packed crystallographic planes. (wikipedia.org)
In most metallic materials, the magnitude of the Burgers vector for a dislocation is of a magnitude equal to the interatomic spacing of the material, since a single dislocation will offset the crystal lattice by one close-packed crystallographic spacing unit. (wikipedia.org)
In edge dislocations, the Burgers vector and dislocation line are perpendicular to one another. (wikipedia.org)
The Burgers vector is significant in determining the yield strength of a material by affecting solute hardening, precipitation hardening and work hardening. (wikipedia.org)
The Burgers vector plays an important role in determining the direction of dislocation line. (wikipedia.org)
2005)/ "Burgers Vector, b". www.princeton.edu. (wikipedia.org)
For edge dislocations, Burgers vector is ___ to the dislocation line. (studystack.com)
The Burgers vector is the direction of the ___ force. (studystack.com)
To better understand the behaviour of dislocations at the microscopic level, this talk studies a lattice model in which these singularities are not present, proving the existence of stable configurations of screw dislocations in a variety of domains with arbitrary net Burgers vector. (warwick.ac.uk)
2) propagation is hindered by a pinning-depinning mechanism influenced by the relative orientation between the Burgers vector and the ledge geometry of the grain boundary and (3) depinning is thermally activated and therefore not purely mechanically driven. (psi.ch)
Constancy of Burgers vector. (classcentral.com)
The identification of single dislocation lines and the determination of their Burgers vector has been a laborious task usually done by hand in the past. (tu-darmstadt.de)
Pure edge dislocations with a [100] projected direction in the (110) plane with a Burgers vector of the type b = a/2[110 ] were also found. (ufs.ac.za)
Detailed examination of thin foils indicates that dislocations presented in this alloy are screw dislocations with ½ a [111] type Burgers vector. (emc-proceedings.com)
There appears to be a high concentration of Frank-type dislocation loops with a [001] Burger's vector in these samples. (uni-bayreuth.de)
The first model is a physically based model that depends on basic physical quantities, such as dislocation densities, Burgers vector, and activation energy. (lsu.edu)
The Burgers vector of the generalized screw dislocation normal to the isotropic base plane and a discontinuous electric potential locates in the isotropic plane, simultaneously a line force and a line charge are acted at the core. (semcs.net)
The deformation of crystals by the conservative glide of dislocations on a single set of crystallographic planes causes shear in the direction of the resultant Burgers vector of the dislocations concerned, a direction which lies in the slip plane. (taylorfrancis.com)
Utilizing a high-fidelity bond order potential, we have applied this method in aluminium to calculate the dislocation core energy as a function of the angle \textbackslashBeta between the dislocation line and Burgers vector. (northwestern.edu)

Burgers vectors and burgers circuit. (classcentral.com)
Burgers vectors that bound the stacking faults glide on intersecting {011} slip planes and react to produce sessile stair rod dislocations. (aip.org)
The deformation is carried by stress-assisted climb of dislocations with periodic Burgers vectors. (mpg.de)
Dislocations with Burgers vectors with components in the periodic and quasiperiodic directions probably move under the action of a chemical force. (mpg.de)
The objective of this study is to explain the crack propagation mechanism due to the activation of out-of-plane slips with their Burgers vectors having no component of the crack growth direction, which exhibits high resistance to fatigue crack growth. (birmingham.ac.uk)
Body-centered cubic metals and alloys irradiated by energetic particles form highly mobile prismatic dislocation loops with a/2 {111} -type Burgers vectors. (ukaea.uk)

The main defects are threading dislocations and stacking faults in both samples. (springer.com)
Abstract: 'Dislocations are geometric lattice defects which are the carriers of plastic deformation in crystals, and the classical approach to modelling them has been to use continuum linear elasticity theory. (warwick.ac.uk)
Friction forces due to the lattice, to point defects and to dislocations. (epfl.ch)
It has become apparent through experimentation at the micro- and nanolevels that the crystalline defects known as dislocations have significant effects on a material's properties. (asme.org)
Hereinafter we will consider microdefects to be local violations of crystal lattice periodicity caused by clusters of point defects (intrinsic or impurity), dislocation loops or dispersed phase precipitates having submicron or micron sizes. (pensoft.net)
Changes in a grain size and grains orientation have been observed together with the presence and nature of nano-scale defects such as dislocation lines, nets and tangles Tungsten has been reported to influence the dislocation density and dynamics in non-irradiated Ta-W alloys during mechanical testing [3]. (emc-proceedings.com)
It offers comprehensive coverage of dislocation phenomena, including a special focus on liquid crystal defects. (sanfoundry.com)

We present a two-dimensional discrete dislocation plasticity framework coupled with vacancy diffusion wherein dislocation motion occurs by both climb and glide. (warwick.ac.uk)
Dislocation cannot end abruptly inside a crystal, dislocation loop, dislocation node, dislocation motion: glide, climb and cross slip. (classcentral.com)
Ice has a very high plastic anisotropy with easy dislocation glide on basal planes, while glide on non-basal planes is much harder. (awi.de)
These dislocations may also glide and move by a combination of glide and climb. (mpg.de)
The 3D-EBSD analysis revealed little misorientation in the crystal, concurrent with the fatigue crack propagation in the coarse laths oriented favourably for dislocation glide in their longitudinal directions. (birmingham.ac.uk)

Inspired by the transient testing experiments we carried out molecular dynamics simulations of stress drops in the regimes similar to those experimentally performed, with the aim to explore the mechanisms responsible for GB accommodation and to verify whether dislocations are still emitted when strain rates after the stress drops are up to 2 or 3 orders of magnitude lower than those usually applied in atomistic deformation simulations. (psi.ch)
However, even at the lowest applied strain rate the grain boundary network can not accommodate all arriving dislocations, illustrating the challenge to determine the rate-limiting deformation mechanisms for experimental conditions. (psi.ch)
This difference is discussed in terms of the characteristic dislocations occurring during deformation. (tu-darmstadt.de)
High temperature deformation, Difusional creep, Dislocation creep. (titech.ac.jp)

It is employed in a study of dislocation plasticity of nanotwinned metals, which can exhibt highest strength and ductility compared with their twin-free counterparts. (tu-darmstadt.de)
Such a scheme becomes unwieldy when considering the large numbers of dislocations involved in common crystal plasticity. (asme.org)
Classical crystal plasticity formulation based on dislocation slip was extended to include the mechanisms of dislocation channelling, with associated strain softening which is observed in many alloys post irradiation. (ukaea.uk)
With our methodology, the dislocation core energy can be accurately accounted for in models of dislocation-mediated plasticity.e accurately accounted for in models of dislocation-mediated plasticity. (northwestern.edu)

Additionally, a new GB-dislocation interaction mechanism is evidenced, where the misfit regions available at the GB assist the propagation of a lattice dislocation on a plane with low resolved shear stress. (psi.ch)
Diffusion paths: lattice, grain boundary, dislocation and surface. (classcentral.com)
Both interstitials and vacancies are eventually removed from the lattice (when they reach sinks such as dislocations or grain boundaries). (doitpoms.ac.uk)
When there is a sufficient supersaturation of vacancies, the disc of vacancies grows and the gap between the planes on either side collapses to form a continuous lattice with a dislocation loop. (doitpoms.ac.uk)
Preliminary structural analyses of the interface region in synthetic olivine-olivine (Fo-Fo82) diffusion couples reveal that the concentration of dislocations at the interface depends on the extent of initial orientational mismatch between the lattice of the two crystals. (uni-bayreuth.de)

Creation and annihilation of dislocations. (epfl.ch)
Unlike most state quantities, dislocation lengths are not conserved and complete representation would require tracking of position, momentum, and interactions, as well as the creation and annihilation of dislocations. (asme.org)

These mechanisms include dislocation cross-slip and dislocation climb. (warwick.ac.uk)
Dislocation climb requires the diffusion of vacancies and hence signi﫿cant amounts of dislocation climb only occur at temperatures above a third of the melting temperature - in these cases mass transport reduces the plastic strain gradients and thereby reducing the effect of specimen size. (warwick.ac.uk)
However, even at lower temperatures, dislocations can surmount small obstacles with the aid of small amounts of climb. (warwick.ac.uk)
The effect of dislocation climb is explored for a range of problems including size effects in bending of crystals, metal-matrix composites and passivated films. (warwick.ac.uk)
Dislocation climb typically tends to reduce strength enhancements that occur with decreasing size but in some surprising cases can also result in strength increases. (warwick.ac.uk)
Dislocation climb. (epfl.ch)

A generalized screw dislocation in the piezoelectric trimaterial with two parallel plane interfaces is studied. (semcs.net)
The singular solution of a generalized screw dislocation in a homogeneous piezoelectric ceramic is used as the basis for solving the piezoelectric trimaterial body. (semcs.net)
Further, the generalized Peach Koehler forces acting on the generalized screw dislocation are considered. (semcs.net)

Vacancy dislocation loops should reduce the volume of the material whilst interstitial dislocation loops should increase it, as seen in the animation above. (doitpoms.ac.uk)
In ion implanted tungsten single crystals, this method revealed and allowed studying 3 nm radius dislocation loops of vacancy and interstitial type [ 8 ] which are almost irresolvable in transmission electron microscopy ( TEM ) images. (pensoft.net)

The coupling of vacancy diffusion with dislocation motion is a true 'multi-scale' problem as vacancy/dislocation interaction is essentially a dislocation core effect. (warwick.ac.uk)
Emission of a vacancy inside the grain after unpinning of the dislocation dipole (CA,AC). (psi.ch)
The purple circled region shows the formation of a vacancy, from a point defect dragged at the jog resulting from the interaction of the two dislocations. (psi.ch)
Furthermore, it is shown that the interaction of two dislocations gliding on parallel slip planes can result in the emission of a vacancy in the grain interior. (psi.ch)

Numerical simulations of the transient temperature field and dislocation density distribution for a recently published silicon crystal heating experiment were carried out. (mdpi.com)
For the M -plane sample, the density of threading dislocations is around 1 × 10 11 cm -2 and the stacking fault density amounts to approximately 2 × 10 5 cm -1 . (springer.com)
In the A -plane sample, a threading dislocation density in the same order was found, while the stacking fault density is much lower than in the M -plane sample. (springer.com)
In Figure 1c , showing a bright field image of the sample cut parallel to the C -plane, a high density of threading dislocations is apparent. (springer.com)
In general, high-resolution microscopy techniques are only useful for considering a few dislocations at a time, but automated high-speed methods are only capable of resolving dislocation densities well above the average density in a typical annealed metal. (asme.org)
We have presented ab initio study, based on density functional theory methods, of full-core edge dislocation impact on basic properties of 4H-SiC semiconductor. (pan.pl)
In alloys with highest tungsten concentration of 10% dislocations form nets of intersected lines with increasing its number density (Fig.1) which directly affects modifications in hardening behaviour of these kinds of materials. (emc-proceedings.com)

While these approaches have many advantages it is often difficult to naturally incorporate atomistic features, such as dislocations, grain boundaries and crystalline anisotropy (particularly in polycrystalline materials), that can alter both microstructure formation and material properties. (warwick.ac.uk)
In the second part two sophisticated analysis algorithms are developed, which allow to extract the complete dislocation network from an atomistic simulation. (tu-darmstadt.de)
This method has unique advantages: it does not require artificial boundary conditions, is applicable for mixed dislocations, and can yield converged results regardless of the atomistic system size. (northwestern.edu)

Dissociation mechanisms: dislocations in face centred cubic metals. (epfl.ch)

Elastic energy of a dislocation. (classcentral.com)
Nonlinear Theory of Dislocations and Disclinations in Elastic Bodies (Lecture Notes in Physics Monographs)" Book Review: The intended audience of this book comprises senior undergraduate and graduate engineering students. (sanfoundry.com)
The text extensively covers Volterra's dislocations in elastic media and their behavior under significant deformations. (sanfoundry.com)

Models typically tend to over-predict the experimentally observed size effects as they neglect a range of dislocation relaxation mechanisms. (warwick.ac.uk)
For similar strains obtained with a strain rate of 1e8/s strain rate as usually applied in MD, both mechanisms are not observed and dislocations slip preferentially on high Schmid factor planes. (psi.ch)
In addition to these classical polygonization processes that involve the recovery of dislocations into boundaries, alternative mechanisms are discussed for the formation of subgrain boundaries that are not related to the crystallography of the host grain. (awi.de)

Partial dislocations and stacking faults. (epfl.ch)

Our approach reveals that at these lower strain rates, GB accommodation processes are enhanced and dislocations are observed to slip on planes experiencing relatively low resolved shear stress. (psi.ch)
The grain-averaged shear in that grain is shown in (d) by the green line, the blue line shows the resolved shear stress on the slipping dislocation. (psi.ch)

Dislocation Theory: A Five-Year Retrospective (Defect and Diffusion Forum)" Book Review: This book is intended for senior undergraduate and graduate engineering students. (sanfoundry.com)

Inset shows a close up of the stress-strain curve for 1 e7/sec showing the discrete stress drops associated with individual dislocation propagation within grains. (psi.ch)

In screw dislocations, they are parallel. (wikipedia.org)

The book presents techniques of nonlinear elasticity that can be used to examine the imperfections in the crystal structure of solids, including dislocations and disclinations that are crucial for understanding the plastic and strength properties of various materials. (sanfoundry.com)

The new method makes this information available within seconds, enabling a quantitative assessment of dislocation processes in large-scale molecular dynamics (MD) simulations. (tu-darmstadt.de)
A robust molecular dynamics simulation method for calculating dislocation core energies has been developed. (northwestern.edu)

Cross-sectional transmission electron microscopy studies often reveal a-type dislocations located either below or above the interfaces in InGaN/GaN structures deposited along the [0001] direction. (pan.pl)

right) Example for the unpinning of a preexisting partial dislocation loop, combined with the nucleation of the trailing partial dislocation. (psi.ch)

EBSD provides information for the characterization of subgrain boundary types and on the dislocations that are likely to be present along the boundary. (awi.de)
EBSD analyses, in combination with light microscopy measurements, are presented and interpreted in terms of the dislocation slip systems. (awi.de)

Elasticity theory: interactions among dislocations. (epfl.ch)

To better explain the experimentally observed dislocation distribution, the Alexander-Haasen model was extended with a critical stress threshold below which no dislocation multiplication occurs. (mdpi.com)
Subtalar dislocation occurs through the disruption of 2 separate bony articulations: the talonavicular and talocalcaneal joints. (physio-pedia.com)
A dislocation of the subtalar joint usually occurs during plantar flexion and the injury is usually a closed injury [11] . (physio-pedia.com)

The high-resolution bulk dislocation characterization is applied to a well-annealed nickel specimen and the results including visualizations of mesoscale structures are presented. (asme.org)

b) The number of dislocation propagation per 1% strain increment as a function of strain for all three strain rates normalized by the number of grains (100). (psi.ch)
For the highest strain rate, the onset of dislocation propagation is delayed, resulting in a stress overshoot. (psi.ch)
The stress distribution is discussed in terms of dislocation formation and propagation. (pan.pl)

Dislocation-free silicon (Si) single crystals are grown with the Czochralski (CZ) and Floating-Zone (FZ) methods. (mdpi.com)

A dislocation-locking mechanism is proposed for this behavior. (aip.org)

Dislocations: edge, screw and mixed. (classcentral.com)

Subtalar dislocations are usually seen when a person suffers a high-energy trauma such as falling from a height (20%) or road traffic accident (48%) [10] . (physio-pedia.com)
Lateral subtalar dislocations - result from forced eversion of a dorsiflexed foot during high-energy trauma. (physio-pedia.com)
But what Mr. McDonough knows is that, with better planning around its quality-of-life priorities, this region can grow without further spoiling its communities and countryside and without shoving off on future generations the high costs of pollution, traffic-clogged roads, unaffordable housing, burger-flipping wages, and the dislocations of farms and other local businesses that come with chain-store sprawl. (mlui.org)
Decagonal single quasicrystals of the composition Al 70 Ni 15 Co 15 have been deformed in situ in a high-voltage transmission electron microscope at 730 ° C along the 10-fold periodic axis to directly observe the dislocation motion. (mpg.de)
Time-honored items like pizza (74%), fried chicken (42%), tacos (41%) and burgers (29%) rank high among comfort foods. (letschatsnacks.com)

This course deals primarily with the physics of dislocation. (epfl.ch)
A Gauge Theory of Dislocations and Disclinations (Lecture Notes in Physics)" Book Review: This book is aimed at undergraduate and graduate students studying materials science and mechanical engineering. (sanfoundry.com)

Frank-Read source Dislocations Callister, William D. Jr. "Fundamentals of Materials Science and Engineering," John Wiley & Sons, Inc. Danvers, MA. (wikipedia.org)
It offers comprehensive and thorough coverage of the fundamentals of dislocation theory. (sanfoundry.com)

A few subgrain boundaries are indicative of prism 〈a〉 slip or slip of 〈a〉 screw dislocations on the basal plane. (awi.de)

The vector's magnitude and direction is best understood when the dislocation-bearing crystal structure is first visualized without the dislocation, that is, the perfect crystal structure. (wikipedia.org)

Dislocations can cross grain boundaries. (studystack.com)

Using analytical electron microscopy techniques different structure of dislocations has been detected with increasing concentration of tungsten in tantalum in non-irradiated samples. (emc-proceedings.com)

We show that these dislocations do not emerge during growth but rather are a consequence of the stress state on lateral surfaces and mechanical processing, making them a post-growth effect. (pan.pl)

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