Atomic-Scale Modeling of the Annihilation of Jogged Screw Dislocation Dipoles

1999 ◽  
Vol 578 ◽  
Author(s):  
T. Vegge ◽  
O. B. Pedersen ◽  
T. Leffers ◽  
K. W. Jacobsen
Keyword(s):  
Molecular Dynamics ◽  
Screw Dislocation ◽  
Atomic Scale ◽  
Atomistic Simulations ◽  
Elastic Band ◽  
Screw Dislocations ◽  
Scale Modeling ◽  
Band Method

AbstractUsing atomistic simulations we investigate the annihilation of screw dislocation dipoles in Cu. In particular we determine the influence of jogs on the annihilation barrier for screw dislocation dipoles. The simulations involve energy minimizations, molecular dynamics, and the Nudged Elastic Band method. We find that jogs on screw dislocations substantially reduce the annihilation barrier, hence leading to an increase in the minimum stable dipole height.

Study of Nanocutting Using Atomic Model

2008 ◽  
Vol 33-37 ◽  
pp. 963-968
Author(s):  
Chun Yi Chu ◽  
Chung Ming Tan ◽  
Yung Chuan Chiou
Keyword(s):  
Molecular Dynamics ◽  
Energy Minimization ◽  
Atomic Scale ◽  
Scale Model ◽  
Atomistic Simulations ◽  
Cutting Depth ◽  
Cutting Deformation ◽  
Simulation Results ◽  
Model Approach

The stress induced in a workpiece under nanocutting are analyzed by an atomic-scale model approach that is based on the energy minimization. Certain aspects of the deformation evolution during the process of nanocutting are addressed. This method needs less computational efforts than traditional molecular dynamics (MD) calculations. The simulation results demonstrate that the microscopic cutting deformation mechanism in the nanocutting process can be regarded as the instability of the crystalline structure in our atomistic simulations and the surface quality of the finished workpiece varies with the cutting depth.

Atomistic Simulation of ½ Screw Dislocations in BCC Tungsten

2008 ◽  
Vol 59 ◽  
pp. 247-252 ◽  
Author(s):  
Jan Fikar ◽  
Robin Schäublin ◽  
Carolina Björkas
Keyword(s):  
Screw Dislocation ◽  
Atomistic Simulation ◽  
Bond Order ◽  
Analytical Approach ◽  
Atomistic Simulations ◽  
Screw Dislocations ◽  
Atom Model ◽  
Embedded Atom ◽  
Bond Order Potential

Atomistic simulations are used to describe the ½<111> screw dislocation in tungsten. Two different embedded atom model (EAM) potentials and one bond-order potential (BOP) are compared. A new analytical approach for constructing asymmetrical screw dislocations is presented.

scholarly journals Atomistic Simulations of Dislocations in Confined Volumes

MRS Bulletin ◽  
2009 ◽  
Vol 34 (3) ◽  
pp. 184-189 ◽  
Author(s):  
P.M. Derlet ◽  
P. Gumbsch ◽  
R. Hoagland ◽  
J. Li ◽  
D.L. McDowell ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Time Scale ◽  
Finite Temperature ◽  
Atomistic Simulation ◽  
Dislocation Nucleation ◽  
Atomic Scale ◽  
Atomistic Simulations ◽  
Complementary Role ◽  
Nanocrystalline Structures ◽  
Strength And Ductility

AbstractInternal microstructural length scales play a fundamental role in the strength and ductility of a material. Grain boundaries in nanocrystalline structures and heterointerfaces in nanolaminates can restrict dislocation propagation and also act as a source for new dislocations, thereby affecting the detailed dynamics of dislocation-mediated plasticity. Atomistic simulation has played an important and complementary role to experiment in elucidating the nature of the dislocation/interface interaction, demonstrating a diversity of atomic-scale processes covering dislocation nucleation, propagation, absorption, and transmission at interfaces. This article reviews some atomistic simulation work that has made progress in this field and discusses possible strategies in overcoming the inherent time scale challenge of finite temperature molecular dynamics.

Molecular Dynamics Simulations of Damage Cascades Creation in Oxide-Particle-Embedded Fe

2017 ◽  
Author(s):  
A. M. Mustafa ◽  
Zhongyu Li ◽  
Lin Shao
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Oxide Particle ◽  
Oxide Dispersion Strengthened ◽  
Atomic Scale ◽  
Scale Modeling ◽  
Alloy Type ◽  
Oxide Particles ◽  
Ods Alloys ◽  
Dynamics Simulations

Oxide-dispersion-strengthened (ODS)alloys have been identified as one promising candidate alloy type for high temperature reactor applications. Understanding irradiation stability of ODS alloys relies on atomic scale modeling such as molecular dynamics simulations. In this study, yttrium and oxygen charges in Y2O3 oxide particles, which are embedded in pure Fe matrix, are optimized to achieve stabilities observed in experiments. Deviation from the optimized charges causes self-explosion and instability of oxide particles. Molecular dynamics simulations further show that under such optimized charge conditions, damage cascade creation and defect developments can be appropriately modeled.

Atomic-Scale Modeling of Low-Energy Ion-Solid Processes

1988 ◽  
Vol 129 ◽  
Author(s):  
Brian W. Dodson
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Low Energy ◽  
Atomic Scale ◽  
Scale Modeling ◽  
Dynamics Simulations

ABSTRACTVarious techniques which have been applied to modeling low-energy (≪ 1 keV) ion-solid interactions on an atomistic scale are described. In addition to their individual strengths, all such methods also have a number of drawbacks, both fundamental and practical. The range of validity, and the problems encountered external to this range, will be outlined for the different approaches. Finally, examples of molecular dynamics simulations of low-energy ion-solid interactions will be presented.

Atomic-Scale Modeling of Low-Energy Ion-Solid Processes

1988 ◽  
Vol 128 ◽  
Author(s):  
Brian W. Dodson
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Low Energy ◽  
Atomic Scale ◽  
Scale Modeling ◽  
Dynamics Simulations

ABSTRACTVarious techniques which have been applied to modeling low-energy (<< 1 keV) ion-solid interactions on an atomistic scale are described. In addition to their individual strengths, all such methods also have a number of drawbacks, both fundamental and practical. The range of validity, and the problems encountered external to this range, will be outlined for the different approaches. Finally, examples of molecular dynamics simulations of low-energy ion-solid interactions will be presented.

Diffusion in Materials by Atomic-Scale Modeling: Exploiting the Predictive Power of Classical and First-Principles Molecular Dynamics

2010 ◽  
Vol 297-301 ◽  
pp. 244-253
Author(s):  
Hervé Bulou ◽  
Christine Goyhenex ◽  
Carlo Massobrio
Keyword(s):  
Molecular Dynamics ◽  
Diffusion Coefficients ◽  
Density Functional ◽  
Diffusion Processes ◽  
Diffusion Mechanism ◽  
Atomic Scale ◽  
Close Link ◽  
Scale Modeling ◽  
Realistic Description

This paper highlights the role played by diffusion processes to achieve a better characterization of structure and dynamics in atomic-scale studies of materials. Two classes of examples are presented. In the first, we take advantage of diffusion coefficients to assess the performances of different exchange-correlation functionals employed within the framework of density functional theory. By calculating the diffusion coefficients one is able to make a choice on the functional best suited to describe a prototypical disordered system, liquid GeSe2. In the second class of examples, we rely on classical molecular dynamics to describe diffusion mechanism on nanostructured substrates. The migration of a Co adatom on a stepped Pt(111) surface is analyzed in detail and correlated to the value of the different diffusion barriers. The diffusion behavior of Au adatoms on the reconstructed Au(111) substrate is described in terms of diffusion isotropy and anisotropy, by comparison with the case of Co/Au(111). Taken altogether, these studies exemplify the close link between diffusion properties, a realistic description of materials and the current level of performances of atomic-scale simulations methods.

Helium Diffusion in Tungsten Studied by Molecular Dynamics Method

2014 ◽  
Vol 789 ◽  
pp. 543-548 ◽  
Author(s):  
Xiao Lin Shu ◽  
Peng Tao
Keyword(s):  
Molecular Dynamics ◽  
Diffusion Equation ◽  
Mean Square Displacement ◽  
Diffusion Path ◽  
Diffusion Barriers ◽  
Dynamics Simulation ◽  
Elastic Band ◽  
Atom Diffusion ◽  
Band Method ◽  
Computer Resources

The interstitial helium (He) atom diffusion in tungsten (W) was studied by the Molecular Dynamics Simulation with the drag method, the Nudged Elastic Band method (NEB) and the mean square displacement (MSD) method. The diffusion barriers and the possible microscopic diffusion path were calculated by the drag method. It has the characteristics of simple, intuitive, and occupies less computer resources, but can't get the diffusion equation. The NEB method is more reasonable than the drag method to calculate the diffusion barriers, and determine the diffusion path which, but the former spends more computer resources than the latter, and it also can't get the diffusion equation. The diffusion equation is obtained by MSD method, including the diffusion per-factor and diffusion barriers. It is suggested that the mechanism of He diffusion changes with difference temperature, which spends the most computer resources among the three methods.

Atomic Scale Simulation of Cross Slip and Screw Dislocation Dipole Annihilation

1998 ◽  
Vol 538 ◽  
Author(s):  
Torben Rasmussen
Keyword(s):  
Screw Dislocation ◽  
Energy Barrier ◽  
Minimum Energy ◽  
Experimental Studies ◽  
Cross Slip ◽  
Atomic Scale ◽  
Atomistic Simulations ◽  
Minimum Energy Path ◽  
Dislocation Dipole ◽  
Single Screw

AbstractAtomistic simulations are used to study cross slip of a single screw dislocation as well as screw dislocation dipole annihilation in Cu. A configuration space path techniquex is applied to determine, without presumptions about the saddle point, the minimum energy path of transition for cross slip. The cross slip process is that proposed by Friedel and Escaig, and the energy of the in-plane constriction initiating cross slip is determined. A minimum stable dipole height much smaller than previously inferred from experimental studies is found. Relaxed screw dislocation dipoles adopt a skew configuration due to the anisotropy of Cu. The path technique is applied to investigate annihilation of stable screw dislocation dipoles, and the energy barrier for annihilation as a function of dipole height is determined for both homogeneous and heterogeneous cross slip leading to the annihilation. The results might be used as quantitative input into meso-/macro-scopical modelling approaches which rely on parameters deduced from either simulation or experiment.

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