Computer Simulations of Epitaxial Interfaces

1988 ◽  
Vol 141 ◽  
Author(s):  
S. A. Dregia ◽  
P. Wynblatt ◽  
C. L. Bauer
Keyword(s):  
Orientation Relationship ◽  
Computer Simulations ◽  
Interfacial Energy ◽  
Boundary Energy ◽  
Enthalpy Of Mixing ◽  
Embedded Atom Method ◽  
Misfit Dislocations ◽  
Maximum Displacement ◽  
Embedded Atom ◽  
Atomic Diameter

AbstractThe embedded-atom method was applied in computer simulations to study epitaxial Cu/Ag interfaces in cube-on-cube orientation relationship. Coherent and semicoherent interfaces were studied with inclinations parallel to (001), (011) and (111). The coherent boundary energy depends strongly on the predicted enthalpy of mixing. The interfacial energy for semicoherent boundaries was highly anisotropic, having its largest value (549 mJ/m2) for the (011) interface and its smallest value (231 mJ/m2) for the (111) interface. The periodic elastic relaxations correspond to networks of misfit dislocations lying in the plane of the interface; the maximum displacement in the (011) interface is about one-third the atomic diameter, but only one-eighth the atomic diameter in the (111) interface.

Monte Carlo Modeling of Interphase Boundaries in Cu-Ag and Cu-Ag-Au Alloys

1990 ◽  
Vol 205 ◽  
Author(s):  
P. Bacher ◽  
P. Wynblatt
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Binary System ◽  
Ternary Alloy ◽  
Embedded Atom Method ◽  
Misfit Dislocations ◽  
Monte Carlo Modeling ◽  
Embedded Atom ◽  
Composition And Structure ◽  
Interphase Boundaries

AbstractMonte Carlo simulation, in conjunction with the embedded atom method, has been used to model the composition and structure of a semicoherent (001) interphase boundary separating coexisting Cu-rich and Ag-rich phases in a binary Cu-Ag alloy. The results are compared with earlier simulations of the same boundary in a Cu-Ag-Au alloy, in which Au was found to segregate to the interface, and the boundary was found to be unstable with respect to break-up into {111} facets. The boundary in the binary system is also unstable to faceting, but displays both {100} as well as {111} facets. It is concluded that Au segregation in the ternary alloy plays an important role in stabilizing the {111} facets. The interplay between the misfit dislocations present at the interface, and the compositional features of the boundary are also discussed.

Some Thermodynamic Properties of NiAl Calculated by Molecular Dynamics Simulations

1988 ◽  
Vol 133 ◽  
Author(s):  
P. C. Clapp ◽  
M. J. Rubins ◽  
S. Charpenay ◽  
J. A. Rifkin ◽  
Z. Z. Yu ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Free Energy ◽  
Boundary Energy ◽  
Alloy System ◽  
Embedded Atom Method ◽  
Interatomic Potentials ◽  
Surface Energies ◽  
Embedded Atom ◽  
Dynamics Simulations ◽  
Anti Phase Boundary

ABSTRACTCalculations of the surface free energy and anti-phase boundary energy as a function of low index orientations and temperature have been determined for equiatomic perfectly ordered bcc NiAl via molecular dynamics computer simulations. The simulations utilized an Embedded Atom Method calculation of the interatomic potentials and volume forces in the Ni-As alloy system. Values of about 0.95, 1.6, 1.9 and 2.0 J/m2 were found for surface energies of the {100}, {110}, {112} and {111} orientations:, respectively. APB energies of about 0.24 and 0.38 J/m2 were determined for {110} and {112} boundaries, respectively. In addition, we have examined the phase stability and relative energies of the ordered bcc, fcc and bct phases at low temperature, and find a bct phase with c/a = 1.32 slightly lower in energy than the bcc, presaging the martensitic transformation that occurs at finite temperatures in more nickel rich alloys.

Ab Initio Electronic Structure Calculations of the Σ 5 (210) [001] Tilt Grain Boundary in Ni3Al

1997 ◽  
Vol 472 ◽  
Author(s):  
Gang Lu ◽  
Nicholas Kioussis
Keyword(s):  
Electronic Structure ◽  
Grain Boundary ◽  
Boundary Energy ◽  
Boundary Region ◽  
Embedded Atom Method ◽  
Full Potential ◽  
Plane Wave Method ◽  
Embedded Atom ◽  
Tilt Grain Boundary ◽  
Linearized Augmented Plane Wave

ABSTRACTThe atomic and the electronic structure of the Σ 5 (210) [001] tilt grain boundary in Ni3Al have been calculated using the full potential linearized-augmented plane-wave method. The strain field normal to the boundary plane and the excess grain boundary volume are calculated and compared with the results obtained using the embedded-atom method (EAM). The interlayer strain normal to the grain boundary oscillates with increasing distance from the grain boundary. The bonding charge distributions suggest that bonding in the boundary region is significantly different from that in the bulk. The grain boundary energy and the Griffith cohesive energy are calculated and compared with the EAM results.

Atomistic Structure and Composition of a Ag/Ni Interphase Boundary

1990 ◽  
Vol 187 ◽  
Author(s):  
P. Gumbsch ◽  
M. S. Daw ◽  
S. M. Foiles ◽  
H. F. Fischmeister
Keyword(s):  
Interphase Boundary ◽  
Minimum Energy ◽  
Embedded Atom Method ◽  
Interface Plane ◽  
Misfit Dislocations ◽  
Abrupt Transition ◽  
Embedded Atom ◽  
Induced Stresses ◽  
Atomistic Structure ◽  
The Ideal

AbstractUsing the embedded atom method we atomistically model the compensation of the misfit induced stresses in a “cube on cube” oriented Ag/Ni bicrystal with (011) interface plane, in which zones of maximum misfit (misfit dislocations) run along the [100] and the [011] directions.The ideal interface corresponds to an abrupt transition between Ag and Ni. The interfacial enthalpy is found to be lowered by the introduction of vacancies on the Ni side (equivalently, vacancies are trapped on the Ni side of the boundary). Pursuing this perspective, we find that the interfacial enthalpy is lowered considerably by the removal of a complete line of Ni atoms along the [011] direction from the Ni side of the boundary. The minimum energy configuration consists of a Ni layer whose atomic density is reduced by 16% sandwiched between the ordinary Ni and Ag lattices.

Computer Simulations of Two-Dimensional Sn-Cu Alloys on (100) and (111) Cu Surfaces

1999 ◽  
Vol 570 ◽  
Author(s):  
Jose F. Aguilar ◽  
R. Ravelo ◽  
M. Baskes
Keyword(s):  
Thin Films ◽  
Computer Simulations ◽  
Embedded Atom Method ◽  
Higher Moments ◽  
Two Dimensional ◽  
Ion Scattering ◽  
Embedded Atom ◽  
Cu Alloys ◽  
Atomic Interactions ◽  
Modified Embedded Atom Method

ABSTRACTWe have performed calculations of Sn deposition on Cu(111) and Cu(100) surfaces. The atomic interactions are described by modified embedded atom method (MEAM) potentials. This is a modification of the embedded atom method (EAM) to include higher moments in the electron density. We find the at low coverages Sn deposited on Cu(111) leads to the formation of a two-dimensional (2D) alloy phase with a p (√3 × √3)-R 30° structure which is stable up to temperatures of 900K. These results are in agreement with ion-scattering experiments of thin films of Sn on Cu(111). For deposition of Sn on Cu(100), a 0.25 monolayer (ML) coverage results in the formation of a stable 2D alloy phase with a p(2 × 2) structure. This result is also in agreement with LEED measurements.

The Structure and Composition of Interphase Boundaries in Ni/Ag-(001) Thin Films Doped with Au

1985 ◽  
Vol 56 ◽  
Author(s):  
S.A. Dregia ◽  
C.L. Bauer ◽  
P. Wynblatt
Keyword(s):  
Thin Films ◽  
Shear Modulus ◽  
Computer Simulations ◽  
Interphase Boundary ◽  
Interaction Potential ◽  
Experimental Studies ◽  
Embedded Atom Method ◽  
Embedded Atom ◽  
Interphase Boundaries

AbstractComputer simulations of the Ni/Ag-(001) interphase boundary have been performed with the Embedded Atom Method. The relaxed atomic configurations, the periodic interaction potential, the shear modulus of the interface, and the interaction of an Au impurity with the interface have been evaluated. In addition, experimental studies have been conducted on the same system; and the structure and composition of the interface have been simultaneously examined.

Stress Induced Martensitic(SIM) Transformations In B2 NiAl Observed in Crack Propagation Computer Simulations

1990 ◽  
Vol 213 ◽  
Author(s):  
Donghyun Kim ◽  
P. C. Clapp ◽  
J. A. Rifkin
Keyword(s):  
Molecular Dynamics ◽  
Martensitic Transformation ◽  
Crack Propagation ◽  
Computer Simulations ◽  
Alloy System ◽  
External Stress ◽  
Embedded Atom Method ◽  
Mode I ◽  
Al Alloy ◽  
Embedded Atom

ABSTRACTIn molecular dynamics studies of 10,000 atom arrays of stoichiometric B2 NiAl containing a crack under external stress in Mode I loading, it has been observed that a martensitic transformation generally occurs (starting in the vicinity of the crack tip) prior to the generation of dislocations and/or the propagation of the crack. The martensitic phase appears to be 2H, in agreement with experimental observations of SIM at higher Ni compositions (62 at % Ni). The interatomic interactions used in the simulations were the Embedded Atom Method (EAM) potentials developed by Voter and Chen [1] for the Ni-Al alloy system.

An Extension of the Embedded Atom Method

1990 ◽  
Vol 193 ◽  
Author(s):  
R. Pasianot ◽  
E. J. Savino ◽  
S. Rao ◽  
D. Farkas
Keyword(s):  
Computer Simulations ◽  
Embedded Atom Method ◽  
Many Body ◽  
Shear Forces ◽  
Embedded Atom ◽  
First Case ◽  
Cauchy Pressure ◽  
The Many ◽  
Three Body ◽  
Embedding Function

For the class of materials in which covalent effects are important, there is still no simple and reliable scheme, adapted to computer simulations, that can handle angle de- pendent forces. Either they are based on the introduction of three body (or higher) [1] interactions, or demand unphysical behavior from the many body functions used [2,3]. In the first case, computer efficiency is considerably low due to the large amounts of calculations required; in the second case a negative curvature of the embedding function must be assumed for materials in which the Cauchy pressure is negative, and this is contrary to the current interpretations of that function.In the present work we derive a method to introduce many body shear forces, suited to computer simulations, which is free from the shortcomings mentioned above.

Variability of Twin Boundary Structure in Computer Simulations of Tensile Twins in Magnesium

2018 ◽  
Vol 385 ◽  
pp. 241-244 ◽  
Author(s):  
Kostianyn Kushnir ◽  
Andriy Ostapovets
Keyword(s):  
Twin Boundary ◽  
Computer Simulations ◽  
Boundary Structure ◽  
Embedded Atom Method ◽  
Interatomic Potentials ◽  
Embedded Atom ◽  
Models Comparison ◽  
Literature Result

Variety of interatomic potentials for magnesium can be found in the literature. Result of computer simulations can be slightly different depending on used potential. Particularly, twin boundary structure with the lowest energy can be different in a frame of different models. Comparison of several popular embedded-atom method potentials is provided. It is shown that either reflection or glide structure of twin boundary has the lowest energy for different potentials.

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