scholarly journals Atomistic calculations of dislocation core energy in aluminium

2017 ◽  
Vol 95 (5) ◽  
Author(s):  
X. W. Zhou ◽  
R. B. Sills ◽  
D. K. Ward ◽  
R. A. Karnesky
Keyword(s):  
Dislocation Core ◽  
Core Energy ◽  
Atomistic Calculations

The Study of Defects in Metals Using High Resolution Transmission Electron Microscopy and Atomistic Calculations

1990 ◽  
Vol 183 ◽  
Author(s):  
M. J. Mills ◽  
M. S. Daw
Keyword(s):  
Grain Boundary ◽  
Good Description ◽  
Dislocation Core ◽  
Thin Foil ◽  
Core Structure ◽  
Embedded Atom ◽  
Pair Potentials ◽  
Transmission Electron ◽  
Atomistic Calculations ◽  
Stringent Test

AbstractThe coupling of HRTEM with atomistic calculations is described for the study of grain boundaries and dislocations in aluminum. HRTEM images of the Σ9 (221) [110] grain boundary are compared with molecular statics calculations using both the Embedded Atom Method (EAM) and two pair potentials. Comparison between observed and simulated images are shown to serve as a stringent test of the theoretical methods. Atomistic calculations can in turn provide threedimensional information about the defect structure. Using the EAM, it is also possible to account for the effects of thin foil geometries on the minimim energy configuration of defects. While these effects are found to be minimal for grain boundary structures, the influence of the thin-foil geometries on the core structure of the 60° dislocation in aluminum is discussed. These comparisons indicate that the EAM function provides a good description of grain boundary structures, but fails to reproduce the observed dislocation core structure due to a low predicted value of the intrinsic stacking fault energy (SFE) on the (111). In contrast, the pair potentials used in this study provide reasonable SFE values, but appear to be less accurate for the prediction of the Σ9 (221) [110] grain boundary structures.

Estimation of the dislocation core energy in BaF2 crystals

1981 ◽  
Vol 16 (5) ◽  
pp. 1426-1428 ◽  
Author(s):  
A. E. Smirnov ◽  
A. A. Urusovskaya
Keyword(s):  
Dislocation Core ◽  
Core Energy

scholarly journals Дислокационные реакции в полуполярном слое GaN, выращенном на вицинальной подложке Si(001) с использованием буферных слоев AlN и 3C-SiC

2019 ◽  
Vol 61 (12) ◽  
pp. 2317
Author(s):  
Л.М. Сорокин ◽  
M.Ю. Гуткин ◽  
A.В. Mясоедов ◽  
A.E. Kaлмыков ◽  
В.Н. Бессолов ◽  
...  
Keyword(s):  
Dislocation Core ◽  
Hydride Vapor Phase Epitaxy ◽  
Dislocation Segment ◽  
Threading Dislocation ◽  
Transmission Electron ◽  
Core Energy ◽  
Half Loop ◽  
Approximation Estimate ◽  
Means Of Transmission ◽  
Semipolar Gan

The interaction between a+c-type and a-type dislocations in thick (up to 14 µm) semipolar GaN layer grown by hydride vapor phase epitaxy on a 3C SiC/Si(001) template has been detailed investigated by means of transmission electron microscopy. It is shown, that the expansion of a dislocation half loop with Burgers vector b=1/3<1-210> during cooling process can be blocked by its reaction with a threading dislocation with b=1/3<1-210> to form a dislocation segment with b=<0001>. This dislocation reaction is discussed in terms of the energy relaxation. The approximation estimate made within the linear tension approach gives the total energy gain ~7.6 eV/Å (that is, in general, ~45.6 keV for the observed screw dislocation segment of length 600 nm formed as a result of the reaction). Using the core energy calculations, the dislocation core contribution was also estimated as ~19.1 keV.

scholarly journals Elastic moduli, dislocation core energy, and melting of hard disks in two dimensions

2000 ◽  
Vol 61 (6) ◽  
pp. 6294-6301 ◽  
Author(s):  
Surajit Sengupta ◽  
Peter Nielaba ◽  
K. Binder
Keyword(s):  
Elastic Moduli ◽  
Dislocation Core ◽  
Two Dimensions ◽  
Hard Disks ◽  
Core Energy

Character angle effects on dissociated dislocation core energy in aluminum

2021 ◽  
Vol 23 (5) ◽  
pp. 3290-3299
Author(s):  
X. W. Zhou ◽  
M. E. Foster
Keyword(s):  
Dislocation Core ◽  
Atomistic Simulations ◽  
Core Energy

Dislocation core energy is an important property in materials mechanics but can only be obtained from atomistic simulations.

Direct structure images of 30° partial dislocation cores in silicon

1987 ◽  
Vol 45 ◽  
pp. 242-243
Author(s):  
J. C. Barry ◽  
H. Alexander
Keyword(s):  
Dislocation Core ◽  
Preparation Technique ◽  
Burgers Vector ◽  
Vector Type ◽  
Sample Preparation Technique ◽  
Lattice Images ◽  
Dislocation Core Structure ◽  
Type Lattice ◽  
Direct Inspection

Dislocations in silicon produced by plastic deformation are generally dissociated into partials. 60° dislocations (Burgers vector type 1/2[101]) are dissociated into 30°(Burgers vector type 1/6[211]) and 90°(Burgers vector type 1/6[112]) dislocations. The 30° partials may be either of “glide” or “shuffle” type. Lattice images of the 30° dislocation have been obtained with a JEM 100B, and with a JEM 200Cx. In the aforementioned experiments a reasonable but imperfect match was obtained with calculated images for the “glide” model. In the present experiment direct structure images of 30° dislocation cores have been obtained with a JEOL 4000EX. It is possible to deduce the 30° dislocation core structure by direct inspection of the images. Dislocations were produced by compression of single crystal Si (sample preparation technique described in Alexander et al.).

Structural analysis of a Σ5 grain boundary in YBa2Cu3O7δ

1993 ◽  
Vol 51 ◽  
pp. 942-943
Author(s):  
J.-Y. Wang ◽  
Y. Zhu ◽  
A.H. King ◽  
M. Suenaga
Keyword(s):  
Grain Boundary ◽  
Lattice Mismatch ◽  
Weak Link ◽  
Coincidence Site Lattice ◽  
Large Angle ◽  
Dislocation Core ◽  
Superconducting Order Parameter ◽  
Outstanding Problem ◽  
Transmission Electron

One outstanding problem in YBa2Cu3O7−δ superconductors is the weak link behavior of grain boundaries, especially boundaries with a large-angle misorientation. Increasing evidence shows that lattice mismatch at the boundaries contributes to variations in oxygen and cation concentrations at the boundaries, while the strain field surrounding a dislocation core at the boundary suppresses the superconducting order parameter. Thus, understanding the structure of the grain boundary and the grain boundary dislocations (which describe the topology of the boundary) is essential in elucidating the superconducting characteristics of boundaries. Here, we discuss our study of the structure of a Σ5 grain boundary by transmission electron microscopy. The characterization of the structure of the boundary was based on the coincidence site lattice (CSL) model.Fig.l shows two-beam images of the grain boundary near the projection. An array of grain boundary dislocations, with spacings of about 30nm, is clearly visible in Fig. 1(a), but invisible in Fig. 1(b).

Energy Law Principles and COVID-19

2020 ◽  
Vol 1 (2) ◽  
pp. 245-247
Author(s):  
Vicente Lopez-Ibor Mayor ◽  
Raphael J. Heffron
Keyword(s):  
Energy Sector ◽  
Economic Recovery ◽  
Low Carbon ◽  
Left Behind ◽  
Core Energy ◽  
Low Carbon Energy ◽  
Energy Law

It is advanced here that a principle-based approach is needed to develop the energy sector during and after COVID-19. The economic recovery that is needed needs to revolve around ensuring that no one is left behind, and it should be an inclusive transition to a secure and stable low-carbon energy future. There are seven core energy law principles that if applied to the energy sector could enable this to be achieved.

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