scholarly journals Study of the embedded atom method of atomistic calculations for metals and alloys. Final report, March 1, 1986--February 29, 1992

1992 ◽  
Author(s):  
R.A. Johnson
Keyword(s):  
Metals And Alloys ◽  
Embedded Atom Method ◽  
Final Report ◽  
Embedded Atom ◽  
Atomistic Calculations

Stucture of 1/2 Dislocations In γ-Tial by High Resolution Tem and Embedded Atom Method Modelling

1994 ◽  
Vol 364 ◽  
Author(s):  
J. P. Simmons ◽  
M. J. Mills ◽  
S. I. Rao
Keyword(s):  
High Resolution ◽  
Atomistic Simulation ◽  
Embedded Atom Method ◽  
Simulation Methods ◽  
Embedded Atom ◽  
A Value ◽  
High Resolution Tem ◽  
Atomistic Calculations ◽  
Range Of Values ◽  
Limit Estimate

AbstractHigh Resolution TEM (HRTEM) observations of a dislocation in γ-TiAl are compared directly with atomistic calculations of dislocation structures performed with atomistic potentials in order to obtain an estimate of the Complex Stacking Fault Energy (γcsf). A value of between 470 and 620 mJ/M2 was obtained. HRTEM observations are presented of a Ti-52AI sample, containing a dislocation with Burgers vector 1/2<110> and 60° line orientation. This image is matched against images simulated from the outputs of Embedded Atom Method (EAM) simulations, using potentials that were fit to bulk γ-TiAl properties. Two atomistic simulation methods were employed in order to give the range of values for γcsf. In the first of these methods, three EAM potentials were used to simulate the stress-free core structure. These were fit so as to produce three different values of γcsf, all other properties being roughly the same as the literature values for γ-TiAI. All of these potentials produced cores that were more extended than the experimental observation. Thus a value of 470 mJ/M2, being the highest value of γcsf obtainable for the EAM potentials, is reported as a low limit estimate of γcsf for γ-TiAl. An upper limit estimate of the value of γcsf was obtained by applying an external ‘Escaig’ stress that forced the Shockley partials to further constrict, simulating the effect of an increase in γcsf, The preliminary value calculated from this procedure was 620 mJ/M2.

Structural Energetics of Thin Coherently Strained Metallic Overlayers

1986 ◽  
Vol 83 ◽  
Author(s):  
Brian W. Dodson ◽  
Paul A. Taylor
Keyword(s):  
Optimization Procedure ◽  
Embedded Atom Method ◽  
Embedded Atom ◽  
Growth Stability ◽  
Atomistic Calculations ◽  
Bimetallic System ◽  
The Stability ◽  
Bimetallic Structures ◽  
Metal Overlayers ◽  
The Continuum

ABSTRACTUnderstanding of the growth, stability, and structural properties of coherently strained metal overlayers has achieved considerable importance because of the recent discovery of unique interfacial electronic states and catalytic properties of such systems. The structural stability of coherently strained metal films grown on a substrate composed of a different and lattice-mismatched metal is determined via atomistic calculations. An equilibrium energy balance criterion is used, which is evaluated with a Monte Carlo annealing optimization procedure in which the structural energy of the bimetallic system is obtained using the embedded atom method. The stability of coherently strained (100) bimetallic structures chosen from combinations of the fcc metals Ag, Au, Cu, Ni, Pd, and Pt has been studied. The predicted critical thicknesses agree remarkably well with experimental results, but disagree quantitatively with the continuum models.

Interfacial Strengthening in Semi-Coherent Metallic Multilayers

1994 ◽  
Vol 362 ◽  
Author(s):  
S. I. Rao ◽  
P. M. Hazzledine ◽  
D. M. Dimiduk
Keyword(s):  
Yield Stress ◽  
Continuum Theory ◽  
Lattice Parameter ◽  
Embedded Atom Method ◽  
Metallic Multilayers ◽  
Parameter Mismatch ◽  
Multilayer Systems ◽  
Embedded Atom ◽  
Atomistic Calculations ◽  
Stress Drops

AbstractExperimental results show that a nanolayered composite structure made of two kinds of metals strengthens dramatically as the layer thickness is reduced. In epitaxial systems, this strengthening has been attributed classically, to the modulus and lattice parameter mismatches between adjacent layers. The modulus mismatch introduces a force between a dislocation and its image in the interface. The lattice parameter mismatch generates stresses and mismatch dislocations which interact with mobile dislocations. In addition to these two interactions, there is the difficulty of operating a Frank-Read source in any very thin layer. However, the calculations suffer from the drawback that elasticity theory is being used at such short range from the dislocations that it is not strictly valid. In this paper the issues in strengthening of multilayer systems are defined within a simple analytical model. Additionally, a parametric approach using the atomistic embedded atom method (EAM), is developed to study, dislocation-interface interactions in metallic multilayers. Preliminary results of the atomistic calculations verify that Koehler strengthening is significant especially when the lamellae are very thin. For thicker lamellae the lattice parameter mismatch effects, which have been modelled within continuum theory, contribute increasingly to the strength. In Cu-Ni, the peak in the yield stress occurs when single dislocations must overcome both barriers. The yield stress drops in thicker lamellae as pile ups of increasing length form in the lamellae, finally conforming to the Hall-Petch equation.

Hrtem Observations Of A Σ=3 {112} Bicrystal Boundary In Aluminum

1992 ◽  
Vol 295 ◽  
Author(s):  
D. L. Medlin ◽  
M. J. Mills ◽  
W. M. Stobbs ◽  
M. S. Daw ◽  
F. Cosandey
Keyword(s):  
Rigid Body ◽  
High Energy ◽  
Low Energy ◽  
Boundary Structure ◽  
Energy Structure ◽  
Embedded Atom Method ◽  
Fcc Metals ◽  
Embedded Atom ◽  
Grain Boundary Structure ◽  
Atomistic Calculations

AbstractWe present here a study of the Σ=3 {112} incoherent twin boundary in aluminum. Atomistic studies of this boundary indicate that several high energy boundary structures may exist, with the lowest energy structure exhibiting a small rigid body shift parallel to the boundary. The observations presented here indicate that the rigid body shift does in fact occur and that its magnitude, as well as the local grain boundary structure, is well predicted by atomistic calculations using the Embedded Atom Method. The low energy boundary configuration is much narrower than the equivalent boundaries that have been observed in the lower stacking fault energy FCC metals.

Atomistic Simulation Study of Controlled Nanostructure Patterning

2003 ◽  
Vol 775 ◽  
Author(s):  
Byeongchan Lee ◽  
Kyeongjae Cho
Keyword(s):  
Diffusion Barrier ◽  
Atomistic Simulation ◽  
Degrees Of Freedom ◽  
Embedded Atom Method ◽  
Surface Kinetics ◽  
Bulk Properties ◽  
Embedded Atom ◽  
Kinetics Of ◽  
Dissociation Barrier ◽  
Strain Dependent

AbstractWe investigate the surface kinetics of Pt using the extended embedded-atom method, an extension of the embedded-atom method with additional degrees of freedom to include the nonbulk data from lower-coordinated systems as well as the bulk properties. The surface energies of the clean Pt (111) and Pt (100) surfaces are found to be 0.13 eV and 0.147 eV respectively, in excellent agreement with experiment. The Pt on Pt (111) adatom diffusion barrier is found to be 0.38 eV and predicted to be strongly strain-dependent, indicating that, in the compressive domain, adatoms are unstable and the diffusion barrier is lower; the nucleation occurs in the tensile domain. In addition, the dissociation barrier from the dimer configuration is found to be 0.82 eV. Therefore, we expect that atoms, once coalesced, are unlikely to dissociate into single adatoms. This essentially tells that by changing the applied strain, we can control the patterning of nanostructures on the metal surface.

Modified embedded-atom method potentials for the plasticity and fracture behaviors of unary fcc metals

2021 ◽  
Vol 103 (9) ◽  
Author(s):  
Zachary H. Aitken ◽  
Viacheslav Sorkin ◽  
Zhi Gen Yu ◽  
Shuai Chen ◽  
Zhaoxuan Wu ◽  
...  
Keyword(s):  
Embedded Atom Method ◽  
Fcc Metals ◽  
Embedded Atom ◽  
Fracture Behaviors ◽  
Modified Embedded Atom Method

scholarly journals Fabrication of Magnesium-Aluminum Composites under High-Pressure Torsion: Atomistic Simulation

2021 ◽  
Vol 11 (15) ◽  
pp. 6801
Author(s):  
Polina Viktorovna Polyakova ◽  
Julia Alexandrovna Pukhacheva ◽  
Stepan Aleksandrovich Shcherbinin ◽  
Julia Aidarovna Baimova ◽  
Radik Rafikovich Mulyukov
Keyword(s):  
Atomistic Simulation ◽  
High Pressure Torsion ◽  
Tensile Tests ◽  
Temperature Treatment ◽  
Embedded Atom Method ◽  
Interface Bonding ◽  
Embedded Atom ◽  
Interlayer Region ◽  
Kinetics Of ◽  
Loading Scheme

The aluminum–magnesium (Al–Mg) composite materials possess a large potential value in practical application due to their excellent properties. Molecular dynamics with the embedded atom method potentials is applied to study Al–Mg interface bonding during deformation-temperature treatment. The study of fabrication techniques to obtain composites with improved mechanical properties, and dynamics and kinetics of atom mixture are of high importance. The loading scheme used in the present work is the simplification of the scenario, experimentally observed previously to obtain Al–Cu and Al–Nb composites. It is shown that shear strain has a crucial role in the mixture process. The results indicated that the symmetrical atomic movement occurred in the Mg–Al interface during deformation. Tensile tests showed that fracture occurred in the Mg part of the final composite sample, which means that the interlayer region where the mixing of Mg, and Al atoms observed is much stronger than the pure Mg part.

scholarly journals An interatomic potential for saturated hydrocarbons based on the modified embedded-atom method

2014 ◽  
Vol 16 (13) ◽  
pp. 6233-6249 ◽  
Author(s):  
S. Nouranian ◽  
M. A. Tschopp ◽  
S. R. Gwaltney ◽  
M. I. Baskes ◽  
M. F. Horstemeyer
Keyword(s):  
Interatomic Potential ◽  
Embedded Atom Method ◽  
Computationally Efficient ◽  
Saturated Hydrocarbons ◽  
Embedded Atom ◽  
Modified Embedded Atom Method

Extension of the computationally efficient modified embedded-atom method to hydrocarbons and polymers.

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