Simple Flexible Boundary Conditions for the Atomistic Simulation of Dislocation Core Structure and Motion

1992 ◽  
Vol 291 ◽  
Author(s):  
Roberto Pasianot ◽  
Eduardo J. Savino ◽  
Zhao-Yang Xie ◽  
Diana Farkas
Keyword(s):  
Atomistic Simulation ◽  
Dislocation Line ◽  
Dislocation Core ◽  
Dislocation Motion ◽  
Peierls Stress ◽  
Rigid Boundary ◽  
The Past ◽  
Structure And Motion ◽  
Linear Effects ◽  
Dislocation Core Structure

ABSTRACTFlexible boundary codes for the atomistic simulation of dislocations and other defects have been developed in the past mainly by Sinclair [1], Gehlen et al.[2], and Sinclair et al.[3]. These codes permitted the use of smaller atomic arrays than rigid boundary codes, gave descriptions of core non-linear effects and allowed fair assessments of the Peierls stress for dislocation motion. Green functions (continuum or discrete) or surface traction forces were used to relax the boundary atoms.A much simpler approach is followed here. Core and mobility effects at the boundary are accounted for by a dipole tensor centered at the dislocation line, whose components constitute six more parameters of the minimization process. Results are presented for [100] dislocations in NiAl. It is shown that, within the limitations of the technique, reliable values of the Peierls stress are obtained.

Dynamics of Dissociated Dislocations in SI: A Micro-Meso Simulation Methodology

1998 ◽  
Vol 538 ◽  
Author(s):  
W. Cai ◽  
V.V. Bulatov ◽  
J.F. Justo ◽  
S. Yip ◽  
A.S. Argon
Keyword(s):  
Atomistic Simulation ◽  
Kinetic Monte Carlo ◽  
Dislocation Core ◽  
Dislocation Motion ◽  
Peierls Stress ◽  
Dislocation Mobility ◽  
Simulation Methodology ◽  
Structure And Dynamics ◽  
Dislocation Behavior ◽  
Stress Dependent

AbstractThe theory of dislocation motion in materials with high Peierls stress relates dislocation mobility to the underlying kink mechanisms. While one has been able to describe certain qualitative features of dislocation behavior, important details of the atomic core mechanisms are lacking. We present a hybrid micro-meso approach to modeling the mobility of a single dislocation in Si in which the energetics of defect cores and kink mechanisms are treated by atomistic simulation, while dislocation motion under applied stress and at finite temperature is described through kinetic Monte Carlo. Three important aspects pertaining to treating the details of local structure and dynamics of kinks are incorporated in our approach: (1) Realistic complexity of (multiple) kink mechanisms in the dislocation core. (2) Full Peach-Koehler formalism for treatment of curved dislocation. (3) Detailed investigation of interaction between partials. This simulation methodology is used to calculate micron-scale dislocation mobility, with no adjustable parameters; specifically we obtain temperature and stress dependent velocity results that can be compared with experimental measurements.

Atomistic Simulation of Dislocation Motion as Determined by Core Structure

1994 ◽  
Vol 350 ◽  
Author(s):  
Kevin Ternes ◽  
Diana Farkas ◽  
Zhao-Yang Xie
Keyword(s):  
Atomistic Simulation ◽  
Dislocation Core ◽  
Dislocation Motion ◽  
Core Structure ◽  
Planar Structure ◽  
Interatomic Potentials ◽  
Atom Type ◽  
The Core ◽  
Embedded Atom ◽  
Structure And Motion

AbstractTwo different interatomic potentials of the embedded atom type were used to study the relationships between dislocation core structure and mobility. Core structures were computed for a variety of dislocations in B2 NiAl. Several non-planar cores were studied as they reacted to applied stress and moved. The results show that in some cases, the dislocation core transforms to a planar structure before the dislocation glides, whereas in some other cases the core retains the non-planar structure at stresses sufficient to sustain glide. The effects of stoichiometry deviations on the core structure and motion were also studied.

Comparison of TEM Observations with Dislocation Core Structure Calcuiations in B2 Ordered Compounds

1990 ◽  
Vol 213 ◽  
Author(s):  
D. Farkas ◽  
R. Pasianot ◽  
E. J. Savino ◽  
D.B. Miracle
Keyword(s):  
Single Crystals ◽  
Computer Simulations ◽  
Slip Plane ◽  
Structural Transition ◽  
Tensile Ductility ◽  
Dislocation Line ◽  
Dislocation Core ◽  
Core Structure ◽  
Dislocation Core Structure

ABSTRACTDislocation core structures have been calculated using atomistic computer simulations in NiAl and other B2 compounds. In the present work the calculated dislocation core structure are correlated with the known deforniatiorn behavior of B2 alloys. It is found that for the high ordering energy compounds <111> dislocations do not split in the simulations, in agreement with the experimental observations. It is also found that core structures for certain <111> and 1/2 <111> dislocations are spread in { 112} planes, which is consistent with the slip plane often reported for these dislocations. For the < 100> dislocations several orientations of the dislocation line produce sessile core configurations, whereas other orientations produce relatively more glissile cores. However, a structural transition of each of these dislocation cores may be required before < 100> dislocations become mobile, and this is consistent with the limited tensile ductility observed in NiAl “soft” single crystals below 200°C. Core structure simulations for < 110> dislocations are also reported and are discussed with respect to the importance of these dislocations in the deformation of NiAl.

Dislocation core structure and motion in pure titanium and titanium alloys: A first-principles study

2022 ◽  
Vol 203 ◽  
pp. 111081
Author(s):  
Tomohito Tsuru ◽  
Mitsuhiro Itakura ◽  
Masatake Yamaguchi ◽  
Chihiro Watanabe ◽  
Hiromi Miura
Keyword(s):  
Titanium Alloys ◽  
First Principles ◽  
Pure Titanium ◽  
Dislocation Core ◽  
Core Structure ◽  
First Principles Study ◽  
Structure And Motion ◽  
Dislocation Core Structure

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.

Dislocation Core Structure and Peierls Stress of B2-Based AlSc in {110} Plane

2016 ◽  
Vol 45 (10) ◽  
pp. 5024-5032
Author(s):  
S. R. Li ◽  
X. Z. Wu ◽  
T. Zhang ◽  
Y. X. Tian ◽  
Z. X. Yan ◽  
...  
Keyword(s):  
Dislocation Core ◽  
Core Structure ◽  
Peierls Stress ◽  
Dislocation Core Structure
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