Determination of the Burgers vector of a dislocation in a Fe-Mn alloy by weak-beam image in HVEM

1978 ◽  
Vol 36 (1) ◽  
pp. 330-331
Author(s):  
Y. Ishida ◽  
H. Ishida ◽  
K. Kohra ◽  
H. Ichinose
Keyword(s):  
High Order ◽  
Simulation Technique ◽  
The Other ◽  
Image Simulation ◽  
Diffraction Vector ◽  
Burgers Vector ◽  
Weak Beam ◽  
Beam Image ◽  
Edge Component

IntroductionA simple and accurate technique to determine the Burgers vector of a dislocation has become feasible with the advent of HVEM. The conventional image vanishing technique(1) using Bragg conditions with the diffraction vector perpendicular to the Burgers vector suffers from various drawbacks; The dislocation image appears even when the g.b = 0 criterion is satisfied, if the edge component of the dislocation is large. On the other hand, the image disappears for certain high order diffractions even when g.b ≠ 0. Furthermore, the determination of the magnitude of the Burgers vector is not easy with the criterion. Recent image simulation technique is free from the ambiguities but require too many parameters for the computation. The weak-beam “fringe counting” technique investigated in the present study is immune from the problems. Even the magnitude of the Burgers vector is determined from the number of the terminating thickness fringes at the exit of the dislocation in wedge shaped foil surfaces.

scholarly journals Determination of the Burgers Vector of a Dislocation by Weak-Beam Image in HVEM

1980 ◽  
Vol 44 (3) ◽  
pp. 288-293
Author(s):  
Yoichi Ishida ◽  
Hidenobu Ishida ◽  
Hideki Ichinose ◽  
Kazutaka Kohra
Keyword(s):  
Burgers Vector ◽  
Weak Beam ◽  
Beam Image

Dislocation Structures in Ni3(Al, Hf)

1996 ◽  
Vol 460 ◽  
Author(s):  
T. Kruml ◽  
B. Viguier ◽  
J. Bonneville ◽  
P. Spätig ◽  
J. L. Martin
Keyword(s):  
Electron Microscopy ◽  
Antiphase Boundary ◽  
Image Simulation ◽  
Compression Tests ◽  
Simulation Techniques ◽  
Weak Beam ◽  
Thin Foils ◽  
Transmission Electron ◽  
Different Temperatures

ABSTRACTSingle crystalline specimens of Ni74.8Al21.9Hf3.3 were subjected to compression tests at different temperatures. Thin foils for transmission electron microscopy observations were prepared from several specimens deformed within and above the yield stress anomaly domain. The dislocation microstructure was studied. The weak beam imaging and image simulation techniques followed by anisotropie elasticity calculations were used for the determination of antiphase boundary energies in both cube and octahedral planes, resulting in values of 237 mJm-2 and 252 mJm-2 respectively. The comparison of the present results with data taken from literature shows the influence of Hf on mechanical properties, dislocation microstructures and APB energies.

Planar distributions of dislocations III. The exact positions of important dislocations when the number in an array is large

1971 ◽  
Vol 320 (1543) ◽  
pp. 527-535 ◽  
Keyword(s):  
Simple Procedure ◽  
Continuous Distribution ◽  
The Other ◽  
General Situation ◽  
Burgers Vector ◽  
Large Numbers ◽  
Discrete Dislocations ◽  
Model Determination ◽  
Exact Positions

It is shown that if large numbers of complete dislocations are piled-up against a coplanar barrier dislocation, the equilibrium positions occupied by those discrete dislocations in the immediate vicinity of the barrier can be found directly from the characteristics, in the barrier’s neighbourhood, of the function representing the situation where all the dislocations are smeared into a continuous distribution, assuming that they have the same Burgers vector. Since such characteristics are readily obtained by examining the relevant singular integral equation for the model, determination of the important dislocation positions becomes a simple procedure. The approach is exact and refers to the limiting situation where the number of dislocations is very large; on the other hand, the smeared-discrete compromise approach (described in earlier papers in this series), in which the important dislocations remain discrete while the remainder are smeared into a continuous distribution, is approximate but is applicable to the more general situation where the number of dislocations is sufficiently large for the distance between the important dislocations to be small compared with the array length.

A Weak-Beam Study of the Microstructure of β-CUZN Deformed in the Domain of Flow Stress Anomaly

1988 ◽  
Vol 133 ◽  
Author(s):  
G. Dirras ◽  
P. Beauchamp ◽  
P. Veyssière
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Flow Stress ◽  
Single Crystals ◽  
Room Temperature ◽  
Burgers Vector ◽  
Weak Beam ◽  
Transmission Electron ◽  
Edge Component ◽  
Imaging Conditions

ABSTRACTβ-brass single crystals oriented along <001> were deformed between room temperature and 300°C. The deformation microstructure and dissociation properties were studied by transmission electron microscopy under weak-beam imaging conditions.Whatever the deformation temperature, superdislocations with <111> Burgers vector and strong edge component dominate within the microstructure. In addition, below the temperature of the flow stress peak (≈ 250°C), the density of screw relative to mixed superdislocations decreases as straining temperature increases. Dissociation does not always occur on the slip plane neither does it proceed exclusively by glide, even in samples deformed at 100°C.

Determination of edge-component Burgers vector of threading dislocations in GaN crystal by using Raman mapping

2018 ◽  
Vol 11 (11) ◽  
pp. 111001 ◽  
Author(s):  
Nobuhiko Kokubo ◽  
Yosuke Tsunooka ◽  
Fumihiro Fujie ◽  
Junji Ohara ◽  
Shoichi Onda ◽  
...  
Keyword(s):  
Threading Dislocations ◽  
Raman Mapping ◽  
Burgers Vector ◽  
Edge Component ◽  
Gan Crystal

scholarly journals Determination of the Burgers Vector of Twin Boundary Dislocations by Weak Beam Method

1984 ◽  
Vol 48 (5) ◽  
pp. 455-460
Author(s):  
Kun-ichi Miyazawa ◽  
Du-bin Cheng ◽  
Hideo Saito ◽  
Minoru Mori ◽  
Yoichi Ishida
Keyword(s):  
Twin Boundary ◽  
Burgers Vector ◽  
Weak Beam ◽  
Beam Method

Determination of the Burgers vector of a dislocation by weak-beam imaging in a HVEM

1980 ◽  
Vol 42 (4) ◽  
pp. 453-462 ◽  
Author(s):  
Yoichi Ishida ◽  
Hidenobu Ishida ◽  
Kazutake Kohra ◽  
Hideki Ichinose
Keyword(s):  
Burgers Vector ◽  
Weak Beam

Weak Beam Imaging and Diffraction Studies of Stacking Faults in Silicon

1976 ◽  
Vol 34 ◽  
pp. 590-591
Author(s):  
T. Y. Tan ◽  
W. K. Tice
Keyword(s):  
Fast Neutron ◽  
Rapid Determination ◽  
Stacking Faults ◽  
Imaging Method ◽  
Large Reduction ◽  
Dislocation Loops ◽  
Fringe Spacing ◽  
Weak Beam ◽  
Kinematical Theory

In studying ion implanted semiconductors and fast neutron irradiated metals, the need for characterizing small dislocation loops having diameters of a few hundred angstrom units usually arises. The weak beam imaging method is a powerful technique for analyzing these loops. Because of the large reduction in stacking fault (SF) fringe spacing at large sg, this method allows for a rapid determination of whether the loop is faulted, and, hence, whether it is a perfect or a Frank partial loop. This method was first used by Bicknell to image small faulted loops in boron implanted silicon. He explained the fringe spacing by kinematical theory, i.e., ≃l/(Sg) in the fault fringe in depth oscillation. The fault image contrast formation mechanism is, however, really more complicated.

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