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.

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.

An embedded-atom-method study of diffusion of an Ag adatom on (111) Ag

1990 ◽  
Vol 68 (9) ◽  
pp. 1035-1040 ◽  
Author(s):  
W. K. Rilling ◽  
C. M. Gilmore ◽  
T. D. Andreadis ◽  
J. A. Sprague
Keyword(s):  
Activation Energy ◽  
Saddle Point ◽  
Surface Diffusion ◽  
Minimum Energy ◽  
Dynamics Simulation ◽  
Embedded Atom Method ◽  
Fixed Position ◽  
Embedded Atom ◽  
Minimization Procedure ◽  
Gradient Energy

The activation energy, vibrational frequency, and surface-diffusion jumps of a single adatom on a perfect (111) surface were studied using the embedded-atom method. The activation energy was determined with a conjugate gradient energy-minimization procedure. The surface adatom was moved in steps across the (111) plane through a saddle point. The adatom position was fixed within (parallel to) the (111) plane; but, the Ag adatom was free to relax, normal to the (111) plane. In this way the adatom was free to ride up over the saddle point; so that at each fixed position within the (111) plane the Ag adatom was free to move to its minimum energy. Also all of the atoms within the Ag crystal were free to relax to minimum-energy positions as the Ag adatom was moved across the surface. The minimum activation energy calculated for adatom diffusion was 0.058 eV. The embedded-atom method was also combined with a molecular dynamics simulation to observe the vibrations of the surface atoms and the adatom and to observe surface-diffusion jumps of the adatom. The adatom jumped to new surface sites at a frequency of approximately 1 × 1012 jumps s−1 at a temperature of 700 K.

Embedded atom calculations of the equilibrium shapes of 5–60 atom palladium nanocrystals

1993 ◽  
Vol 8 (3) ◽  
pp. 455-461 ◽  
Author(s):  
A. Sachdev ◽  
R.I. Masel
Keyword(s):  
Minimum Energy ◽  
Wide Distribution ◽  
Embedded Atom Method ◽  
Palladium Clusters ◽  
Embedded Atom ◽  
Equilibrium Shapes ◽  
The Stability ◽  
Highly Strained ◽  
Palladium Particles ◽  
Particle Shapes

The embedded atom method (EAM) has been used to compare the stability of a series of small palladium clusters with 5–60 atoms and a variety of shapes. It is found that the 13- and 55-atom icosahedra and cubo-octahedra are stable at 0 K. However, other sized icosahedra and cubo-octahedra are unstable at 0 K. Upon annealing, the icosahedra and cubo-octahedra reconstruct into nonpolyhedral structures which are highly strained. The strained structures are much more stable than the icosahedron or cubo-octahedron except when there are 13 or 55 atoms in the cluster. Further, there are many disordered shapes which are within 0.01 eV of the minimum energy structures at all cluster sizes including 13 and 55 atoms. We observe transitions between these low energy structures in Monte Carlo calculations. These results suggest that at equilibrium one should rarely observe polyhedral palladium particles. Instead, most of the particles should be disordered. Further, there should be a wide distribution of particle shapes in agreement with experiment.

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.

Determination of Energy Minima for Dissimilar Metal Interfaces

1991 ◽  
Vol 229 ◽  
Author(s):  
Paul Shewmon ◽  
Suliman Dregia
Keyword(s):  
Minimum Energy ◽  
Embedded Atom Method ◽  
Orientation Relationships ◽  
Particle Rotation ◽  
Fcc Metals ◽  
Dissimilar Metal ◽  
Embedded Atom ◽  
Rotation Methods ◽  
Metal Interfaces

AbstractRelative orientations which correspond to minimum energy can be found by particle rotation methods, both for particles on free surface and particles inside a solid. For common fcc metals (Ni,Ag,Cu,Ag) the minimum energy orientations predicted by Embedded Atom Method calculations correspond well with experimental observations. Epitaxial studies of growth on (001)Cu and (111)Cu show the observed orientation relationships of vapor deposited Ag and Au are consistent with EAM calculations and the limited particle rotation experiments available.

Core Structure And Mobility Of a <101] Dislocations In L10 TiAl

1994 ◽  
Vol 364 ◽  
Author(s):  
S. Rao ◽  
C. Woodward ◽  
J. Simmons ◽  
D. Dimiduk
Keyword(s):  
Elastic Properties ◽  
Friction Stress ◽  
Core Structure ◽  
Line Orientation ◽  
Embedded Atom Method ◽  
Shockley Partial ◽  
Embedded Atom ◽  
The Ideal

AbstractAn empirical atomistic potential, fit to the structural and elastic properties of L10 TiAl within the embedded atom method (EAM), is used to simulate the mobility of two possible planar forms of a<101] dislocations in a model L10 compound. The two configurations examined were: the planar SISF-APB-CSF coupled (P core) and the decomposed 1/2<110]-SISF-SESF coupled (D core). Six different line orientations are considered for the P core: 0° (screw), 30°, 60°, 90° (edge), 120° and 150°. The ‘ideal’ friction stress at 0°K of a<101] dislocations in the P form is found to be a function of line orientation, with the close packed line directions, <101] (screw) and <110] (60°), having friction stresses ranging from 0.001–0.002μ. Previously calculated results on the friction stress of a/2<110] dislocations, using an identical potential are consistently higher than the friction stress of a<101] dislocations. Simulations of the interaction of glide strains with the D core for the 60° (line directions < 110]) and 120° (line directions <011]) orientations show that the Shockley partial trailing the SESF in the D core is strongly pinned. The dislocation moves by extension of SESF when glide stresses are applied with SESF as the trailing fault.

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.

The Accommodation of Lattice Mismatch on the (111) Interphase Boundary Plane in FCC Metals

1990 ◽  
Vol 209 ◽  
Author(s):  
P. Gumbsch ◽  
H.F. Fischmeister
Keyword(s):  
Lattice Mismatch ◽  
Boundary Plane ◽  
Embedded Atom Method ◽  
Misfit Dislocations ◽  
Embedded Atom ◽  
Interfacial Energies ◽  
Large Lattice ◽  
Metal Metal ◽  
Large Lattice Mismatch ◽  
Triangular Network

ABSTRACTUsing the embedded atom method we atomistically model the accommodation of the lattice nismatch and study the propertiesof the misfit dislocations in parallel oriented bicrystals. We calculate and analyze in detail the excess interfacial energies on the (100) and (111) boundary planes. The Ag/Ni system is chosen as a model system for metal/metal interfaces with a large lattice mismatch.Among the possible boundary planes in parallel oriented fcc bicrystals, the ones with terminating {111} planes arc energetically most favourable and are most often observed in experiments. This can be explained by a detailed analysis of the elastic strain fields in the interfaces, which correspond to networks of misfit dislocations. While the misfit dislocations on the (100) and (011) planes have a ½[01ī] Burgers vector, those on (111) can dissociate into misfit partials. The elastic strains connected with the misfit partials are, of course, much smaller than those for other types of misfit dislocations. The misfit partials form a triangular network within the boundary plane.

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.

Sign in / Sign up

Export Citation Format

Share Document