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.

Relaxation of Misfit Dislocations at Nodes

2014 ◽  
Vol 783-786 ◽  
pp. 515-520 ◽  
Author(s):  
Shuai Shao ◽  
Jian Wang ◽  
Amit Misra ◽  
Richard G. Hoagland
Keyword(s):  
Misfit Dislocation ◽  
Mechanical Stability ◽  
Experimental Studies ◽  
Atomistic Simulations ◽  
Misfit Dislocations ◽  
Formation Processes ◽  
Coherent Interface ◽  
Core Energy ◽  
Structures And Properties ◽  
Coherent Interfaces

Experimental studies proved that structures and properties of misfit dislocations and their intersections (nodes) in semi-coherent interfaces strongly affect thermal and mechanical stability of interface. Employing atomistic simulations, we reveal that misfit dislocation lines can exhibit a spiral pattern (SP) or remain straight in association with dislocation character at nodes. By analyzing nodes formation processes in terms of kinetics and energetics, we found that the variation is ascribed to the competition between core energy of misfit dislocation and interface stacking fault energy with respect to coherent interface.

scholarly journals Dislocations as a Tool for Nanostructuring Advanced Materials

Physchem ◽  
2021 ◽  
Vol 1 (3) ◽  
pp. 225-231
Author(s):  
Vladyslav Turlo
Keyword(s):  
High Resolution ◽  
Transport Properties ◽  
Large Scale ◽  
Functional Materials ◽  
Dislocation Core ◽  
Solute Segregation ◽  
Advanced Materials ◽  
Atomistic Simulations ◽  
Experimental Characterization ◽  
Nanoscale Features

Dislocations present unique opportunities for nanostructuring advanced structural and functional materials due to the recent discoveries of linear complexions thermodynamically stable nanoscale features with unique chemistry and structure confined at dislocations. The formation of such features is driven by solute segregation near the dislocation core and results in the stabilization of dislocations, altering mechanical, thermodynamic, and transport properties of the final material. This perspective article gives an overview of the recent discoveries and predictions made by high-resolution experimental characterization techniques, as well as large-scale atomistic simulations in the newly emerging field of linear complexions.

Fundamentals of Atomistic Simulations

2006 ◽  
Author(s):  
Vasily Bulatov ◽  
Wei Cai
Keyword(s):  
First Principles ◽  
Large Scale ◽  
Dislocation Core ◽  
Boltzmann Distribution ◽  
Atomistic Simulations ◽  
Computationally Efficient ◽  
Interacting Electrons ◽  
Subsequent Discussion ◽  
Necessary And Sufficient ◽  
Interacting Atoms

Fundamentally, materials derive their properties from the interaction between their constituent atoms. These basic interactions make the atoms assemble in a particular crystalline structure. The same interactions also define how the atoms prefer to arrange themselves in the dislocation core. Therefore, to understand the behavior of dislocations, it is necessary and sufficient to study the collective behavior of atoms in crystals populated by dislocations. This chapter introduces the basic methodology of atomistic simulations that will be applied to the studies of dislocations in the following chapters. Section 1 discusses the nature of interatomic interactions and introduces empirical models that describe these interactions with various degrees of accuracy. Section 2 introduces the significance of the Boltzmann distribution that describes statistical properties of a collection of interacting atoms in thermal equilibrium. This section sets the stage for a subsequent discussion of basic computational methods to be used throughout this book. Section 3 covers the methods for energy minimization. Sections 4 and 5 give a concise introduction to Monte Carlo and molecular dynamics methods. When put close together, atoms interact by exerting forces on each other. Depending on the atomic species, some interatomic interactions are relatively easy to describe, while others can be very complicated. This variability stems from the quantum mechanical motion and interaction of electrons [15, 16]. Henceforth, rigorous treatment of interatomic interactions should be based on a solution of Schrödinger’s equation for interacting electrons, which is usually referred to as the first principles or ab initio theory. Numerical calculations based on first principles are computationally very expensive and can only deal with a relatively small number of atoms. In the context of dislocation modelling, relevant behaviors often involve many thousands of atoms and can only be approached using much less sophisticated but more computationally efficient models. Even though we do not use it in this book, it is useful to bear in mind that the first principles theory provides a useful starting point for constructing approximate but efficient models that are needed to study large-scale problems involving many atoms.

Manipulation of Stresses in Metallic Thin Films by Alloying

1994 ◽  
Vol 356 ◽  
Author(s):  
A. S. Nandedkar
Keyword(s):  
Thin Films ◽  
Aluminum Alloy ◽  
Free Surface ◽  
Grain Boundary ◽  
Dislocation Core ◽  
Boundary Plane ◽  
Structural Defects ◽  
Atomistic Simulations ◽  
Metallic Thin Films ◽  
Copper Aluminum

AbstractAtomistic simulations were used to study the configurations of defects in copper aluminum alloy (2% copper, 98% aluminum). In the presence of free surface, the copper atoms migrated towards the surface. When the aluminum cell (about 2000 atoms) contained a dislocation, copper atoms segregated near the dislocation core on the compressional side. In presence of a grain boundary, copper atoms moved into the boundary plane. The segregation in these simulations resulted from reduction in localized strain near the structural defects.

Trends in Dislocation Core Structures and Mechanical Behavior in B2 Aluminide

1994 ◽  
Vol 364 ◽  
Author(s):  
C. Vailhe ◽  
D. Farkas
Keyword(s):  
High Temperature ◽  
Mechanical Behavior ◽  
Deformation Mechanism ◽  
Dislocation Core ◽  
Peierls Stress ◽  
Atomistic Simulations ◽  
Dislocation Behavior ◽  
B2 Structure

AbstractIn an effort to understand the deformation mechanism in high temperature B2 intermetallics, atomistic simulations were carried out for dislocation cores in a series of compounds exhibiting the B2 structure (FeAl, NiAl, CoAl). A comparison was made on the basis of core structures, dislocation splittings and Peierls stress values. The (110) and (112) γ surfaces were computed for these three compounds. The importance of the APB values and the maximum shear faults for explaining the dislocation behavior is discussed.

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

Dislocation Core Structure Evolution During Dislocation Glide in FCC Lattices

2003 ◽  
Vol 779 ◽  
Author(s):  
M.A. Soare ◽  
R.C. Picu
Keyword(s):  
Shear Stress ◽  
Elastic Field ◽  
Dislocation Core ◽  
Peierls Stress ◽  
Atomistic Simulations ◽  
Structure Evolution ◽  
Dislocation Glide ◽  
The Core ◽  
Fcc Lattice ◽  
Dislocation Core Structure

AbstractA dislocation core model is developed in terms of a singular decomposition of the elastic field surrounding the defect in a power series of 1/rn. The decomposition is a Laurent expansion beginning with the term corresponding to the Volterra dislocation and continuing with a series of dipoles and multipoles. The analysis is performed for an edge dislocation in an fcc lattice. The field surrounding the dislocation is derived by means of atomistic simulations. The coefficients of the series expansion are determined from the elastic field using path independent integrals. When loaded by a shear stress smaller than the Peierls stress, the core distorts. The distortion up to the instability (Peierls stress) is monitored based on the variation of these coefficients. The stacking fault separating the two partials is characterized, by using a similar procedure, as a source of elastic field.

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.

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