Simple structural unit model for core-dependent properties of symmetrical tilt boundaries

1983 ◽  
Vol 17 (8) ◽  
pp. 1027-1030 ◽  
Author(s):  
R.W. Balluffi ◽  
A. Brokman
Keyword(s):  
Structural Unit ◽  
Unit Model ◽  
Tilt Boundaries ◽  
Symmetrical Tilt

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.

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.

A Study of the Dependence of the Structure of Σ = 3 Tilt Boundaries in Gold on the Inclination of the Boundary Plane

1992 ◽  
Vol 278 ◽  
Author(s):  
Gui Jin Wang ◽  
V. Vitek
Keyword(s):  
Structural Unit ◽  
Atomic Level ◽  
Boundary Plane ◽  
Many Body ◽  
Chain Unit ◽  
Unit Model ◽  
Tilt Boundaries ◽  
A Chain ◽  
The Many ◽  
The Relationship

AbstractThe atomic structure of Σ = 3 tilt boundaries with variously inclined boundary planes has been studied using the many body potentials for gold. A chain unit model, analogous to the structural unit model, describes the relationship between different boundaries. The basic units in this model are units of the (111) and (112) twin boundaries and the model corresponds to atomic level faceting into these boundaries.

Microstructures of a-axis oriented YBCO films made by hybrid plasma sputtering

1995 ◽  
Vol 10 (4) ◽  
pp. 803-809 ◽  
Author(s):  
W. Ito ◽  
A. Oishi ◽  
S. Mahajan ◽  
Y. Yoshida ◽  
T. Morishita
Keyword(s):  
Electron Microscopy ◽  
Grain Boundary ◽  
Anisotropic Growth ◽  
Plan View ◽  
Plasma Sputtering ◽  
Transmission Electron ◽  
Hybrid Plasma ◽  
Tilt Boundaries ◽  
Symmetrical Tilt ◽  
Twist Boundaries

Microstructures of a-axis oriented YBa2Cu3O7−x films made by newly developed de 100 MHz hybrid plasma sputtering were investigated using transmission electron microscopy (TEM). The films deposited on (110) NdGaO3 and (100) SrTiO3 substrates were found to grow in a perfect epitaxial fashion and with clear interface. The plan view of the TEM image showed that both films were comprised of two kinds of grains having the c axis aligning along two perpendicular directions in the plane with equal probability. The structures of the grain boundary, however, were found to be very different for the two films from the plan views. The film on NdGaO3 showed a lot of twist boundaries, while the film on SrTiO3 consisted of many symmetrical tilt boundaries and basal-plane-faced tilt boundaries. The type of grain boundary is determined by the anisotropic growth rates of the film between c direction and a-b direction.

Study of Dynamic Embrittlement in Alloy Bicrystals

1996 ◽  
Vol 458 ◽  
Author(s):  
R. G. Muthiah ◽  
J. A. Pfaendtner ◽  
C. J. McMahon ◽  
P. Lejcek ◽  
V. Paidar
Keyword(s):  
Growth Rate ◽  
Steady State ◽  
Crack Growth Rate ◽  
Grain Boundary ◽  
Crack Growth ◽  
Tilt Axis ◽  
Tilt Boundaries ◽  
Symmetrical Tilt ◽  
Dynamic Embrittlement ◽  
Crack Growth Rates

ABSTRACTIn a kinetic model [1] for the phenomenon of dynamic embrittlement, the cracking rate is predicted to be proportional to the diffusivity of the embrittling species along the grain boundary. To test this model, bicrystals of Cu-Sn and Fe-Si with Σ5 symmetrical tilt boundaries are used in which tin and sulfur, respectively, are the embrittling elements. The diffusivities parallel and perpendicular to the tilt axis are expected to be different, therefore the crack growth rates in these two directions should vary in the same ratio as the diffusivities.Preliminary measurements of crack growth rate along the [100] direction in the Cu-Sn alloy bicrystal are presented. The cracking occurred by decohesion along the grain boundary with almost no observable plasticity. The steady state crack growth was found to be approximately 10∼6 m/sec.

Structural Unit Models for High Angle Symmetrical Tilt Boundaries in Ordered Compounds with the Ll2 Structure

1984 ◽  
Vol 39 ◽  
Author(s):  
D. Farkas
Keyword(s):  
Grain Boundary ◽  
Structural Unit ◽  
Boundary Energy ◽  
Coordination Shell ◽  
Interatomic Potentials ◽  
Two Phase ◽  
Fcc Metals ◽  
Tilt Boundaries ◽  
Hard Sphere Models ◽  
Fcc Materials

ABSTRACTHard sphere models were used to determine densest configurations in symmetrical [100] and [110] tilt boundaries in compounds with the Ll2 structure. The minimum allowed interatomic distances used in these models were estimated from interatomic potentials and the structures of the intermetallic phases in the binary system. The structural unit model is used to analyze the possible ground states for ordering.Two different cases were analyzed corresponding to compounds with “soft” potentials (i.e. Cu3 Au) and “hard” potentials (i.e. Ni3Al). For the Cu3Au type the grain boundary structures obtained were similar to those reported by other investigators for pure fcc metals. Several boundaries were found to be a “two phase” structure, differing in composition and ordering state. This leads to a certain degree of clustering in the boundaries. The contribution of clustering to the grain boundary energy is calculated in a point approximation based on the first coordination shell.For compounds of the Ni3Al type the structures that are densest were found to be generally diffetent from the low energy configurations of boundaries in, pure fcc metals and Cu3 Au. These configurations preserve order, but are much less dense. The possibility of grain boundary “phases” that are not present in other fcc materials may constitute an explanation for the extreme GB weakness observed in Ni3Al and other Ll2 compounds with high ordering energy.

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.

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