scholarly journals Фактор предпочтения базисной краевой дислокационной петли в цирконии. Численный анализ

2020 ◽  
Vol 62 (12) ◽  
pp. 2087
Author(s):  
А.В. Бабич ◽  
В.Ф. Клепиков ◽  
П.Н. Остапчук
Keyword(s):  
Elastic Anisotropy ◽  
Elastic Field ◽  
Elastic Interaction ◽  
Growth Theory ◽  
Hexagonal Crystal ◽  
Bias Factor ◽  
Area Of Influence ◽  
Hexagonal Crystals ◽  
Toroidal Geometry

Recent numerical calculations of the diffusion coefficients of radiation point defects in hexagonal crystals have made it clear that the main assumption of the radiation growth theory of zirconium (DAD - diffusional anisotropy difference) does not allow one to describe the radiation growth correctly. Thus, the elastic ideology (EID - elastic interaction difference), based on the concept of the flow bias factor, remains relevant. Therefore, the bias factor for the basic edge loop of zirconium in a toroidal reservoir was calculated numerically (using the finite difference method), taking into account the elastic anisotropy of the hexagonal crystal. The toroidal geometry of the reservoir makes it possible to calculate the flows for a loop of any size and without any correction of the elastic field in its area of influence. The dependences of the loop bias factor on its radius and nature are obtained for various sink densities. The essential role of the form of the boundary condition on the outer surface of the reservoir is shown. The prospects for further research in the construction of the theory of the radiation growth of zirconium based on the elastic ideology are discussed.

scholarly journals BIAS OF BASAL DISLOCATION LOOP IN ZIRCONIUM

2021 ◽  
pp. 29-34
Author(s):  
A.V. Babich ◽  
P.N. Ostapchuk
Keyword(s):  
Numerical Calculation ◽  
Dislocation Loop ◽  
Point Defects ◽  
Function Method ◽  
Elastic Field ◽  
Its Region ◽  
Elastic Interaction ◽  
Basal Dislocation ◽  
Hexagonal Crystals ◽  
Toroidal Geometry

An analytical expression for the elastic interaction energy of radiation point defects of the dipole type with the basal dislocation loop of the hcp metal is obtained using the Green's function method for hexagonal crystals in the Krener approach. It was used for numerical calculation of the bias for the basal dislocation loop of zirconium in a toroidal reservoir. The toroidal geometry of the reservoir allows one to perform the calculation for a loop of any size and without any correction of the elastic field in its region of influence. The dependencies of the loop bias on its radius and nature are obtained for various shapes of dipole defects.

Origin of the alternate bright/dark contrast in HREM images of hexagonal crystals, particularly 6H-SiC

1993 ◽  
Vol 51 ◽  
pp. 914-915
Author(s):  
J.S. Bow ◽  
R.W. Carpenter ◽  
M.J. Kim
Keyword(s):  
High Resolution ◽  
Incident Beam ◽  
Hexagonal Crystal ◽  
Detailed Explanation ◽  
Similar Character ◽  
High Resolution Images ◽  
The Difference ◽  
Zigzag Shape ◽  
Hexagonal Crystals ◽  
Dark Contrast

A prominent characteristic of high-resolution images of 6H-SiC viewed from [110] is a zigzag shape with a period of 6 layers as shown in Fig.1. Sometimes the contrast is same through the 6 layers of (0006) planes (Fig.1a), but in most cases it appears as in Fig.1b -- alternate bright/dark contrast among every three (0006) planes. Alternate bright/dark contrast is most common for the thicker specimens. The SAD patterns of these two types of image are almost same, and there is no indication that the difference results from compositional ordering. O’Keefe et al. concluded this type of alternate contrast was due to crystal tilt in thick parts of the specimen. However, no detailed explanation was given. Images of similar character from Ti3Al, which is also a hexagonal crystal, were reported by Howe et al. Howe attributed the bright/dark contrast among alternate (0002) Ti3Al planes to phase shifts produced by incident beam tilt.

Contemporary Machiavellian theses "The strategy of the role of the absurd state as a model"

2020 ◽  
pp. 3
Author(s):  
Ali Hussein Hameed ◽  
Saif Hayder AL.Husainy
Keyword(s):  
International Relations ◽  
Decision Maker ◽  
Turning Point ◽  
Information Revolution ◽  
Main Hypothesis ◽  
The Subject ◽  
Area Of Influence ◽  
The Right ◽  
Modern Technologies

In the anarchism that governs the nature and patterns of international relations characterized by instability and uncertainty in light of several changes, as well as the information revolution and the resulting developments and qualitative breakthroughs in the field of scientific and advanced technological knowledge and modern technologies.  All of these variables pushed toward the information flow and flow tremendously, so rationality became an indispensable matter for the decision maker as he faces these developments and changes. There must be awareness and rationality in any activity or behavior because it includes choosing the best alternative and making the right decision and selecting the information accurately and mental processing Through a mental system based on objectivity, methodology, and accumulated experience away from idealism and imagination, where irrationality and anarchy are a reflection of the fragility of the decision-maker, his lack of awareness of the subject matter, his irresponsibility, and recklessness that inevitably leads to failure by wasting time and Effort and potential. The topic acquires its importance from a search in the strategies of the frivolous state and its characteristics with the ability to influence the regional, and what it revealed is a turning point in how to adapt from the variables and employ them to their advantage and try to prove their existence. Thus, the problem comes in the form of a question about the possibility of the frivolous state in light of the context of various regional and international events and trends. The answer to this question stems from the main hypothesis that (the aim which the frustrating state seeks to prove is that it finds itself compelled to choose several strategies that start from the nature of its characteristics and the goals that aim at it, which are centered in the circle of its interests in the field of its struggle for the sake of its survival and area of influence).

Computer Simulation of ao Screw Dislocations in Ni3Al

1990 ◽  
Vol 213 ◽  
Author(s):  
T.A. Parthasarathy ◽  
D.M. Dimiduk ◽  
C. Woodward ◽  
D. Diller
Keyword(s):  
Computer Simulation ◽  
Screw Dislocation ◽  
Elastic Anisotropy ◽  
Elastic Interaction ◽  
Embedded Atom Method ◽  
Interaction Torque ◽  
Embedded Atom ◽  
Reduced Height ◽  
Plane Step ◽  
Simulation Results

ABSTRACTDissociation of the ao<110> screw dislocation in Ni3Al was studied using the embedded atom method of computer simulation. The dissociation occurred predominantly along the {111} plane, however, a {001}-plane step occurred in the APB at the center of the configuration. When a pair of ao/2<110> superpartials initially separated in the {111} plane was relaxed, the step formed once again but with a reduced height. When the pair was relaxed from larger distances the step was not formed. The results indicate that the elastic interaction “torque” due to elastic anisotropy is responsible for the formation of the {001} APB step. When a stress was applied to these dislocation configurations by simulation, results confirmed that the step in the APB and the octahedral cross-slipped-core dissociations can be significant barriers to glide of the screw dislocation.

3D simulations of warm and hot Jupiter atmospheres: the role of 3D mixing in shaping CH4-to-CO conversion pathways

2021 ◽  
Author(s):  
Maria Zamyatina ◽  
Eric Hebrard ◽  
Nathan Mayne ◽  
Benjamin Drummond
Keyword(s):  
Chemical Structure ◽  
Three Dimensional ◽  
Chemical Species ◽  
Radiation Chemistry ◽  
3D Simulations ◽  
Horizontal Advection ◽  
Co Conversion ◽  
Area Of Influence ◽  
Different Parts

&lt;p&gt;We present results from a set of cloud-free simulations of exoplanet atmospheres using a coupled three-dimensional (3D) hydrodynamics-radiation-chemistry model. We report in particular our investigation of the thermodynamic and chemical structure of the atmospheres of HAT-P-11b and WASP-17b and their comparison with the results for the atmospheres of HD 189733b and HD 209458b presented in Drummond et al. (2020). We found that the abundances of chemical species from simulations with interactive chemistry depart from their respective abundances computed at local chemical equilibrium, especially at higher latitudes. To understand this departure, we analysed the CH&lt;sub&gt;4&lt;/sub&gt;-to-CO conversion pathways within the Venot et al. (2019) reduced chemical network used in our model using a chemical network analysis. We found that at steady state nine CH&lt;sub&gt;4&lt;/sub&gt;-to-CO conversion pathways manifest in our 3D simulations with interactive chemistry, with different pathways dominating different parts of the atmosphere and their area of influence being determined by the vertical and horizontal advection and shifting between planets.&lt;/p&gt;

Elastic Interaction of Defects on Crystal Surfaces

1999 ◽  
Vol 121 (2) ◽  
pp. 129-135 ◽  
Author(s):  
Demitris Kouris ◽  
Alonso Peralta ◽  
Karl Sieradzki
Keyword(s):  
Interaction Energy ◽  
Surface Defects ◽  
Film Growth ◽  
Crystal Surface ◽  
Elastic Field ◽  
Elastic Interaction ◽  
Flow Mode ◽  
Elastic Model ◽  
Far Field ◽  
Embedded Atom

Surface defects corresponding to adatoms, vacancies and steps interact, affecting and often dominating kinetic processes associated with thin-film growth. A discrete harmonic model for the evaluation of the interaction energy between surface defects is presented. It is based on the concept of eigenstrains and allows for the accurate evaluation of the elastic field, both at the immediate vicinity of the defects, as well as in the far field. Results for the interaction energy suggest conditions for which a body-centered-cubic crystal surface will grow in a stable, two-dimensional, step-flow mode. In order to verify the accuracy of the discrete elastic model, we present results of atomic simulations that incorporate Embedded Atom Method (EAM) potentials. The discrete elastic model results compare favorably with results from our atomic EAM simulations and agree with the far-field predictions of continuum elastic theory.

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