Dissociation of asymmetric ∑9, ∑27a and ∑81d 〈110〉 tilt boundaries

Forwood, C. T.; Clarebrough, L. M.

doi:10.1016/0001-6160(84)90149-4

Cited by 31 publications

(16 citation statements)

References 16 publications

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“…3j, the (1 1 I)( 1 15) ATGB dissociates into triangular regions bounded by two (1 1 I)( 1 1 1) coherent twins and one (1 12)( 1 12) incoherent twin. This dissociation of the C = 9 into C = 3 boundaries has been reported earlier by several authors (Clarebrough and Forwood 1980, Forwood and Clarebrough 1984, Goodhew et al 1978, Krakow and Smith 1986 and is quite remarkable, since the planar (1 1 I)( 1 15) ATGB has the lowest (LJ) or second lowest (EAM) energy and is also the C = 9 GB with the smallest planar unit cell. However, if the total energy of the dissociated boundary is added up and normalized to the planar, undissociated interface area, one finds, using the C3 GB energies in the table, a total energy per unit area of 347mJm-' and 573mJm-', respectively, for the EAM and LJ potentials.…”

Section: Grain-boundary Structures and Relaxationssupporting

confidence: 82%

Low-energy configurations of symmetric and asymmetric tilt grain boundaries

Merkle

Wolf

1992

Philosophical Magazine A

118

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Section: Grain-boundary Structures and Relaxationssupporting

confidence: 82%

Low-energy configurations of symmetric and asymmetric tilt grain boundaries

Merkle

Wolf

1992

Philosophical Magazine A

118

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“…It seems that a match of the (1 1 5) and (1 1 1) planes at the interface gives a 'lock structure' for displacement of the upper crystal relative to the lower crystal along certain directions (see figure 11 and the discussion there). In this case, the It is worth mentioning that, dissociation of the 9 [1 1 0]-tilt (1 1 5)/(1 1 1) asymmetric tilt GB into a triangular prism bounded by two coherent twin boundaries and a 3 (11 2) symmetric tilt GB has already been observed experimentally in the annealed bulk polycrystal sample of a Cu alloy [50]. The triangular prism observed in that work is quite similar to the ones shown in figures 8(b) and (d).…”

Section: Al By Comparing Figure 6 With Figure 5 (And Also the Curvesmentioning

confidence: 66%

Shear responses of $[\bar{1}\,1\,0]$ -tilt {1 1 5}/{1 1 1} asymmetric tilt grain boundaries in fcc metals by atomistic simulations

Wan

2013

Modelling Simul. Mater. Sci. Eng.

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The shear response of the 3 [1 1 0]-tilt (11 5)/(1 1 1) and 9 [1 1 0]-tilt (1 1 5)/(1 1 1) asymmetric tilt grain boundaries (GBs) in fcc metals Cu and Al has been studied by atomistic simulation methods with the embedded atom method interatomic potentials and with a bicrystal model. It is found that the structure of the GBs studied can be well described by the coincidence site lattice (CSL) theory. Shear of these GBs at room temperature along eight different directions within the GB plane shows that these two types of GBs can transform between each other by the formation of a coherent twin boundary. The structure transformation of the GBs can also take the form of GB sliding, GB sliding-migration coupled motion, GB faceting, GB 9R structure formation, etc, depending on the shear directions adopted and the material involved (Cu or Al). The detailed structure transformation mechanisms have been analyzed with the aid of the CSL-DSC (displacement shift complete) theory. Several structure transformation paths adherent to these two types of GBs have been identified for the activation of the GB sliding-migration coupled motion. It is concluded that, although CSL-DSC theory can be applied to describe the sliding-migration coupled motion of the GBs studied, some other effects such as the shear direction within the GB plane and the bonding characteristics of the materials should also play a significant role in the shear response of these GBs.

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“…The dissociation of a planar GB into two or more GBs must be associated with a lowering of the GB free energy. It is well known from TEM observations that triangular regions are often formed in C = 9 GBs in fcc metals (Clarebrough and Forwood, 1980;Forwood and Clarebrough, 1984;. Figure 7A shows a sequence of such features along a (1 15) (1 11) facet in Au.…”

Section: Grain Boundary Dissociationsmentioning

confidence: 85%

Atomic-Scale Grain Boundary Relaxation Modes in Metals and Ceramics

Merkle

1997

Microsc Microanal

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The atomic-scale structure of tilt grain boundaries has been studied by high-resolution electron microscopy (HREM) in several ceramics and metals such as NiO, yttria stabilized zirconia, Au, and Al. It is found that when grain boundaries are formed between two crystals a considerable variety of modes of relaxations, i.e., the rearrangements of atoms in and near the grain boundary core are possible, depending on grain boundary geometry and the interatomic interactions. The atomic relaxations within and near the grain boundary core often include relaxations that involve the formation of stacking faults in low-stacking-fault energy fcc materials. Grain boundary dissociations are also observed for several grain boundary geometries. Computer simulations of grain boundary structures in metals have in general been able to reproduce the relaxation features at least on a qualitative level. In contrast, ceramic grain boundaries typically are more complex and not always tractable by simple computer relaxation procedures, since the formation of point defects and partial occupancy of atomic columns may be involved in the relaxation processes. It is found that when a boundary is not allowed to relax to its lowest energy state due to geometrical constraints, a multitude of grain boundary core structures can exist. Such conditions are expected to be characteristic for nanocrystalline materials. Because of its close connection to grain boundary properties, quantification of the volume expansion by HREM techniques is an important goal of grain boundary research. Image simulations of grain boundaries suggest that for most materials of interest the 3-fold astigmatism must be corrected to better than 100 nm to achieve the desired accuracies.

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Dissociation of asymmetric ∑9, ∑27a and ∑81d 〈110〉 tilt boundaries

Cited by 31 publications

References 16 publications

Low-energy configurations of symmetric and asymmetric tilt grain boundaries

Low-energy configurations of symmetric and asymmetric tilt grain boundaries

Shear responses of $[\bar{1}\,1\,0]$ -tilt {1 1 5}/{1 1 1} asymmetric tilt grain boundaries in fcc metals by atomistic simulations

Atomic-Scale Grain Boundary Relaxation Modes in Metals and Ceramics

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