Favored Boundaries in the Structural Unit Model of Grain Boundaries

1990 ◽  
Vol 193 ◽  
Author(s):  
M. Khantha ◽  
V. Vitek ◽  
M. Goldman
Keyword(s):  
Grain Boundaries ◽  
Structural Unit ◽  
High Index ◽  
Unit Model ◽  
Tilt Boundaries ◽  
Low Symmetry

ABSTRACTA systematic geometrical procedure for predicting favored boundaries in the structural unit model is presented. The method is applicable to both symmetric and asymmetric tilt boundaries. The predictions are confirmed by modeling the structures of tilt boundaries belonging to low symmetry ( and [221]) axes in f.c.c. and b.c.c. structures. The results confirm the applicability of the structural unit model for relatively high-index tilt axes.

scholarly journals Effect of Grain Boundary Structure on Grain Boundary Diffusivities in the Au/Ag System

1990 ◽  
Vol 209 ◽  
Author(s):  
Qing Ma ◽  
R. W. Balluffi
Keyword(s):  
Thin Film ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Tilt Angle ◽  
Structural Unit ◽  
Boundary Structure ◽  
Grain Boundary Structure ◽  
Unit Model ◽  
Tilt Boundaries ◽  
Accumulation Method

ABSTRACTGrain boundary chemical diffusivities for a series of symmetric [001] tilt boundaries in the Au/Ag system were measured by the surface accumulation method using newly developed thin-film multi-crystal specimens, in which the grain boundaries feeding the accumulation surface were all of the same type. Possible effects due to segregation at the grain boundaries and surfaces were avoided. CSL boundaries of low-Σ ( i.e., 5, 13, 17, 25) and also more general boundaries with tilt angles between the low-Σ orientations were selected. The diffusivities were found to vary monotonically with tilt angle ( i.e., no cusps at low-Σ's were found) in a manner consistent with the Structural Unit model.

Prediction of Energies of Tilt Boundaries in Al-Pb Alloy

2007 ◽  
Vol 1056 ◽  
Author(s):  
Y. Purohit ◽  
D. L. Irving ◽  
R. O. Scattergood ◽  
D. W. Brenner
Keyword(s):  
Grain Boundaries ◽  
First Principles ◽  
Density Functional ◽  
First Principles Calculations ◽  
Pure System ◽  
Embedded Atom ◽  
Unit Model ◽  
Tilt Boundaries ◽  
Embedded Atom Method Potential ◽  
Analytic Potential

ABSTRACTEnergies for symmetric tilt grain boundaries in pure Al and in Al with substitutional Pb defects at coincident sites along the grain boundaries were calculated using a modified embedded atom method potential and density functional theory. The agreement between the analytic potential, the first principles calculations and experiment is reasonably good for the pure system. For the Al-Pb system both the analytic potential and first principles calculations predict that Pb segregation to the interface is energetically preferred compared to the dilute solution. The application of a disclination structural unit model to calculating grain boundary energies over the entire range of tilt angles is also explained.

Atomistic Structure of High Index Surfaces

1996 ◽  
Vol 440 ◽  
Author(s):  
Batsirai Mutasa ◽  
Diana Farkas
Keyword(s):  
Structural Unit ◽  
Structural Features ◽  
Low Energy ◽  
High Index ◽  
Interatomic Potentials ◽  
Embedded Atom ◽  
Unit Model ◽  
Ordered Alloys ◽  
Energy Surfaces ◽  
Atomistic Structure

AbstractInteratomic potentials of the embedded atom (EAM) type were used to study the atomistic structure of high index surfaces in metals and ordered alloys. The results show that a structural unit model can be developed to model the structure of the high index surfaces on the basis of the structure of a few low energy surfaces. The model can predict the structural features and give an estimate of the energies of the higher index surfaces. We present examples of Fe, B2 FeAl and NiAl.

Computer simulation on surfaces and [001] symmetric tilt grain boundaries in Ni, Al, and Ni3Al

1989 ◽  
Vol 4 (1) ◽  
pp. 62-77 ◽  
Author(s):  
S. P. Chen ◽  
D. J. Srolovitz ◽  
A. F. Voter
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Structural Unit ◽  
Boundary Energy ◽  
Boundary Structure ◽  
Grain Boundary Energy ◽  
Local Composition ◽  
Embedded Atom ◽  
Grain Boundary Structure ◽  
Unit Model

We have used “local volume” (embedded atom) type potentials to study the surfaces and grain boundaries of Ni, Al, and Ni3Al. The simulations show that with appropriately fit potentials, the surface and grain boundary structure can be realistically calculated. The surface rippling and relaxation show good agreement with experiments. The energies of most surfaces and grain boundaries also agree with existing data. The structural unit model for grain boundaries in Ni3Al shows the same generic units as in pure metals, but with large variations due to distortions and multiplicity. The utility of the structural unit model is thus more limited for alloys. The grain boundary energies were found to be the highest for Al-rich Ni3Al grain boundaries, and depend significantly on the local composition of the grain boundary. The cusps in the grain boundary energy as a function of misorientation angle are different for different grain boundary stoichiometries. The Ni3Al grain boundaries have approximately the same grain boundary energy and cohesive energy as that of Ni.

Experimental evidence for a structural unit model of quasiperiodic grain boundaries in aluminum

1991 ◽  
Vol 6 (7) ◽  
pp. 1461-1468 ◽  
Author(s):  
P.A. Deymier ◽  
M. Shamsuzzoha ◽  
J.D. Weinberg
Keyword(s):  
Grain Boundaries ◽  
Experimental Evidence ◽  
Structural Unit ◽  
Geometrical Description ◽  
Unit Model

This paper presents a geometrical description of aperiodic grain boundaries within the framework of a quasiperiodic lattice. Experimental evidence is given in support of a structural unit model of quasiperiodic [100]45°twist and [100]45°twist plus tilt grain boundaries in aluminum.

Disclination-structural unit model of grain boundaries

1989 ◽  
Vol 59 (5) ◽  
pp. 1113-1118 ◽  
Author(s):  
V. Yu. Gertsman ◽  
A. A. Nazarov ◽  
A. E. Romanov ◽  
R. Z. Valiev ◽  
V. I. Vladimirov
Keyword(s):  
Grain Boundaries ◽  
Structural Unit ◽  
Unit Model

A Description of Preferential Sites for Vacancy Formation on Grain Boundaries in Copper by Structural Unit Model

2017 ◽  
Vol 898 ◽  
pp. 1351-1355
Author(s):  
Ke Tong ◽  
Fei Ye ◽  
Ya Kun Wang ◽  
Feng Zhou
Keyword(s):  
Molecular Dynamics ◽  
Grain Boundaries ◽  
Structural Unit ◽  
Local Stress ◽  
Dynamics Simulation ◽  
Structural Units ◽  
Symmetric Tilt ◽  
Unit Model ◽  
Large Tensile Stress ◽  
Local Stress Field

The preferential sites for vacancies on a series of symmetric tilt grain boundaries in copper have been investigated by molecular dynamics simulation. The regularity of preferential sites for vacancies on these boundaries can be described by the structural unit model. This is essential because of the correspondence between the geometries of the structural units and the local stress field. The vacancies are energetically preferred at the sites with relatively large tensile stress, and these sites are the corner sites of the structural units. Moreover, these preferential sites are mainly related to the structural unit types irrespective of which grain boundary that the structure units locate in. Therefore, the preferential sites for vacancies on various grain boundaries formed by combinations of certain structural units can be readily described and predicted by the structural unit model.

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