Measurements of misorientation angles over a large distance in strongly coupled grain boundaries

1999 ◽  
Vol 9 (2) ◽  
pp. 1630-1633 ◽  
Author(s):  
M. Mironova ◽  
Guoping Du ◽  
K. Salama
Keyword(s):  
Grain Boundaries ◽  
Large Distance ◽  
Strongly Coupled ◽  
Misorientation Angles

From meandering to straight grain boundaries: Improving the structures of artificially induced grain boundaries in superconducting YBa2Cu3Oy bicrystals

1997 ◽  
Vol 12 (11) ◽  
pp. 3029-3035 ◽  
Author(s):  
Xiao-Feng Zhang ◽  
Volk R. Todt ◽  
Dean J. Miller
Keyword(s):  
Thin Film ◽  
Grain Boundaries ◽  
Film Deposition ◽  
Ybco Bulk ◽  
Transmission Electron ◽  
Ybco Superconductors ◽  
Film Deposition Rate ◽  
Melt Texture ◽  
Key Aspects ◽  
Misorientation Angles

This paper presents several key aspects of our approach to preparing artificially induced [001] tilt grain boundaries (GB's) with uniform, well-defined structures in YBa2Cu3Oy (YBCO) superconductors. GB structures formed in thin film and bulk bicrystals, respectively, will be compared. In YBCO thin film bicrystals, meandering rather than planar GB's are formed. Using a low film deposition rate has been demonstrated to reduce the magnitude of meander significantly, but complete elimination of the meander has not yet been accomplished. Thus, we have developed a dual-seeded-melt-texture process to produce uniform, planar GB's with controllable misorientation angles in YBCO bulk bicrystals. Transmission electron microscopy (TEM) studies reveal a remarkably planar and simple configuration on different length scales. Such a simple structure allows for an insightful interpretation of transport behavior across individual GB's.

Characterization of Zinalco Alloy Superplastically Deformed Using Orientation Imaging Microscopy

2009 ◽  
Vol 1242 ◽  
Author(s):  
Ramos A. Mitsuo ◽  
Martínez F. Elizabeth ◽  
Negrete S. Jesús ◽  
Torres-Villaseñor G.
Keyword(s):  
Grain Size ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Superplastic Deformation ◽  
Orientation Imaging Microscopy ◽  
Grain Boundary Sliding ◽  
Boundary Misorientation ◽  
Average Grain Size ◽  
Grain Boundary Misorientation ◽  
Misorientation Angles

ABSTRACTZinalco alloy (Zn-21mass%Al-2mass%Cu) specimens were deformed superplastically with a strain rate (ε) of 1×10-3 s-1 at homologous temperature (TH) of 0.68 (5 ). It was observed neck formation that indicate nonhomegeneus deformation. Grain size and grain boundaries misorientation changes, due superplastic deformation, were characterized by Orientation Imagining Microscopy (OIM) technique. It was studied three regions in deformed specimens and the results were compared with the results for a specimen without deformation. Average grain size of 1 mm was observed in non-deformed specimen and a fraction of 82% for grain boundary misorientation angles with a grain boundaries angles between 15° and 55° was found. For deformed specimen, the fraction of angles between 15° and 55° was decreced to average value of 75% and fractions of low angle (<5°) and high angle (>55°) misorientations were 10% and 15% respectively. The grain size and high fraction of grain boundary misorientation angles between 15° and 55° observed in the alloy without deformation, are favorable for grain rotation and grain boundary sliding (GBS) procces. The changes observed in the fraction of favorable grain boundary angles during superplastic deformation, shown that the superplastic capacity of Zinalco was reduced with the deformation.

scholarly journals The five-dimensional parameter space of grain boundaries

2015 ◽  
Vol 471 (2181) ◽  
pp. 20150442 ◽  
Author(s):  
A. P. Sutton ◽  
E. P. Banks ◽  
A. R. Warwick
Keyword(s):  
Grain Boundaries ◽  
Degrees Of Freedom ◽  
Geodesic Distance ◽  
Rotational Symmetry ◽  
Boundary Misorientation ◽  
Dimensional Parameter ◽  
Orthogonal Subspace ◽  
The Mean ◽  
Misorientation Angles ◽  
Three Degrees Of Freedom

To specify a grain boundary at a macroscopic length scale requires the specification of five degrees of freedom. We use a specification in which three degrees of freedom associated with the boundary misorientation are in an orthogonal subspace from two associated with the mean boundary plane. By using Rodrigues vectors to describe rotations, we show how paths through these subspaces may be characterized. Some of these paths correspond to physical processes involving grain boundaries during microstructural evolution. Exploiting the orthogonality of the subspaces, a metric to measure ‘distance’ between two boundaries is defined in terms of the minimum set of rotations required to map one boundary on to the other. We compare our metric with others that have appeared. The existence of rotational symmetry in face-centred cubic crystals leads to as many as 2304 equivalent specifications of a boundary. We illustrate this multiplicity of descriptions for the (111) twin and a more general boundary. We present an algorithm to evaluate the geodesic distance between two boundaries, and apply it to identify the path along which the distance between these two boundaries is minimized. In general, the shortest path does not involve descriptions of boundary misorientations with the smallest misorientation angles.

scholarly journals Particularities of changes in internal structure of nanocrystalline Ni under mechanical loading

2019 ◽  
Vol 221 ◽  
pp. 01025
Author(s):  
Dmitrij Kryzhevich ◽  
Aleksandr Korchuganov ◽  
Konstantin Zolnikov
Keyword(s):  
Grain Boundaries ◽  
Triple Junction ◽  
Shear Loading ◽  
Stacking Fault ◽  
Grain Sizes ◽  
Compressive Stresses ◽  
Nucleation Mechanisms ◽  
Constrained Conditions ◽  
Misorientation Angles ◽  
Nanocrystalline Sample

Molecular dynamics study of the plasticity nucleation mechanisms in a Ni nanocrystalline sample under shear loading in the constrained conditions was carried out. The studied Ni sample consisted of nine grains of the same size with large misorientation angles relative to each other. In one of the directions, grippers were simulated, to which compressive forces and shear with a constant velocity were applied. In two other directions, periodic boundary conditions were used. It is shown that plasticity nucleation occurs in the region of the triple junction. At the same time, in the region of the triple junction, in the zone of which the stacking fault will be formed, tensile stresses are realized along one of the adjacent grain boundaries, and compressive stresses occur along the other. An increase in stresses in the triple junction zone leads to the formation of a stacking fault, which moves to the volume of one of the grains. Another mechanism of plasticity in nanocrystalline nickel is the migration of grain boundaries, which leads to a significant change in grain sizes.

In-Situ 1Mev Tem and Hrem Study of the Deformation and the Transformation of Symmetrical Tilt Grain Boundaries in Ge and Si.

1993 ◽  
Vol 319 ◽  
Author(s):  
Jany. Thibault ◽  
X. Baillin ◽  
J. Pelissier ◽  
J.L. Putaux ◽  
H.M. Michaud
Keyword(s):  
Grain Boundaries ◽  
Deformation Temperature ◽  
In Situ Tem ◽  
Final Structure ◽  
Different Types ◽  
Symmetrical Tilt ◽  
Misorientation Angles

AbstractThe evolution under deformation of symmetrical GBs in Si and Ge has been studied both by in-situ TEM and HREM. The influence of the strain conditions (tension or compression) on the final structure through the entrance of different types of dislocations will be discussed. The influence of the deformation temperature on the multiplicity of the structures has been observed in a particular range of misorientation angles.

scholarly journals Energetic and thermal properties of tilt grain boundaries in graphene/hexagonal boron nitride heterostructures

2015 ◽  
Vol 08 (03) ◽  
pp. 1550038 ◽  
Author(s):  
Mingchao Wang ◽  
Guangping Zhang ◽  
Huisheng Peng ◽  
Cheng Yan
Keyword(s):  
Thermal Properties ◽  
Boron Nitride ◽  
Grain Boundaries ◽  
Hexagonal Boron Nitride ◽  
Electronic Devices ◽  
Thermal Conductance ◽  
Interfacial Thermal Conductance ◽  
Non Equilibrium Molecular Dynamics ◽  
Dynamics Simulations ◽  
Misorientation Angles

Graphene/hexagonal boron nitride (G/h-BN) heterostructure has attracted tremendous research efforts owing to its great potential for applications in nanoscale electronic devices. In such hybrid materials, tilt grain boundaries (GBs) between graphene and h-BN grains may have unique physical properties, which have not been well understood. Here we have conducted non-equilibrium molecular dynamics simulations to study the energetic and thermal properties of tilt GBs in G/h-BN heterostructures. The effect of misorientation angles of tilt GBs on both GB energy and interfacial thermal conductance are investigated.

scholarly journals The Structure Effect on Selective Growth in Recrystallization

Texture ◽  
1975 ◽  
Vol 2 (1) ◽  
pp. 35-44 ◽  
Author(s):  
V. Ju. Novikov
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Secondary Recrystallization ◽  
Primary Recrystallization ◽  
Grain Boundary Mobility ◽  
Effective Mobility ◽  
The Matrix ◽  
The Difference ◽  
Grain Misorientation ◽  
Misorientation Angles

The effect of the dependence of grain boundary mobility on misorientation angle and that of structure of the matrix on the growth selectivity during primary and secondary recrystallization are discussed. It was found that the longer is the distance travelled by the growing grain boundaries and the wider the range of the misorientation angles between the new grains and the matrix, the less is the difference between the grain boundary mobilities of the growing grains, necessary for the manifestation of growth selectivity. So during secondary recrystallization the latter is more manifest. In primary recrystallization after moderate deformations, the growth selectivity will be the least obvious when the deformed matrix consists of small differently oriented areas at whose borders new grains nucleate simultaneously. The secondary grain boundaries should be characterized by “effective” mobility, which depends on the number of the adjacent grains and their dimensions, as well as on the growing grain misorientation in relation to these grains. In the small grained material without a texture, the effective boundary mobilities of any grains are equal, and so the growth selectivity in such a material is non-existing.

scholarly journals Базовые элементы структуры границ зерен наклона. Часть 2. Оси разориентации [110] и [111]-=SUP=-*-=/SUP=-

2021 ◽  
Vol 63 (1) ◽  
pp. 55
Author(s):  
А.В. Векман ◽  
Б.Ф. Демьянов
Keyword(s):  
Grain Boundaries ◽  
Atomic Structure ◽  
Pair Potential ◽  
Structural Vacancy ◽  
Many Body ◽  
Structural Units ◽  
Symmetric Tilt ◽  
Vacancy Model ◽  
Body Potential ◽  
Misorientation Angles

The computer simulation methods have been applied to calculate structure and energy of symmetric tilt grain boundaries (GB) with the misorientation axes [110] and [111]. The calculations have been carried out with the use of the structural-vacancy model. The study of the atomic structure has been carried out within the entire range of misorientation angles. The reverse density of coincidence sites in special grain boundaries has amounted Σ≤57. The calculations have been carried out with the use of the Morse pair potential and the Cleri-Rosato many-body potential. When calculated with different potentials, the dependence of GB energy on the misorientation angle has a similar form, and the atomic structure completely coincides. It has been shown that the structure of any GB with the misorientation axes [110] and [111] may be represented by a limited number of basic structural units. All found basic structural units defined as units of A, B, C and D types are based on the structures of special grain boundaries. Such special GBs shall be Σ3(111), Σ3(112), Σ11(113) and Σ9(114) for GBs with the misorientation axis [110], and as regarding GBs with the misorientation axis [111], such special GBs shall be Σ3(112), Σ7(123) and Σ13(134). Ranges of angles within which certain basic structural units are found have been defined.

The role of boundary plane: HREM investigation of the atomic structure of grain boundaries in gold

1988 ◽  
Vol 46 ◽  
pp. 588-589
Author(s):  
K. L. Merkle
Keyword(s):  
Grain Boundaries ◽  
Atomic Structure ◽  
Large Angle ◽  
Boundary Plane ◽  
Low Energy ◽  
Site Density ◽  
Atomic Relaxation ◽  
Tilt Boundaries ◽  
Misorientation Angles

Computer simulations of large-angle grain boundaries (GBs) have indicated the importance of local atomic relaxation, rigid body translations, and of the boundary plane in determining GB energy. Experimental observations of GB structure often find GB faceting, which is an indication that some GB planes are preferred over others. Investigations of the atomic structure of large-angle >001> tilt GBs in NiO have shown, along with symmetrical GB con-figuations, the presence of asymmetric GBs of the type which has at least one of the crystals terminated at the boundary by a low index plane. Such boundaries are thought to be of low energy. For studying the role of the GB plane in a metallic GB we chose in the present work two <011> tilt boundaries in Au. The misorientation angles (θ) were selected such that one bicrystal orientation (θ=39°) was close to the Σ=9 reciprocal coincident site density, while the other (θ=55°) was near the misorientation for which (111) and (100) planes are parallel to each other (θ=54.74°). The latter misorientation is also close to Σ=41 (θ=55.88°).

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