A new model for {10<ovl>1</ovl>2} twin growth in hcp metals

Serra, A.; Bacon, D. J.

doi:10.1080/01418619608244386

Cited by 240 publications

(143 citation statements)

References 14 publications

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“…With this restriction overcome, it has been possible to revisit the 2(a)). The current simulations confirm the earlier finding [5] that this disconnection moves with the twin boundary along its riser (the basal plane of one of the crystals) because twinning dislocations can move past it by glide and self-compensated climb.…”

Section: Discussionsupporting

confidence: 79%

“…Decomposition into products that change the structure of the boundary does not occur. Second, it was found in [5] that a 60°-mixed dislocation decomposes when entering the interface, thereby changing its structure and creating interfacial disconnections. More detail follows below.…”

Section: Modelmentioning

confidence: 99%

“…The dislocation is attracted to, and absorbed spontaneously by, the twin boundary in this reaction when less than about 8 nm from it. In [5] it decomposed into a b -5/-6 disconnection line and three b 2/2 twinning disconnections ( Fig. 2(a)).…”

Section: Modelmentioning

confidence: 99%

“…They move with the twin boundary by conservative climb along their riser [5,16], thereby supplying the twinning disconnections necessary to keep the boundary moving.…”

Section: Modelmentioning

confidence: 99%

“…First, the earlier simulations with rigid boundary conditions showed that a straight, perfect dislocation near a twin boundary may be absorbed by it spontaneously, thereby creating an interfacial step with dislocation character [5]. (Such an interfacial line defect is known as a 'disconnection' [6].)…”

mentioning

confidence: 99%

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Interaction of a moving { } twin boundary with perfect dislocations and loops in a hcp metal

Serra

Bacon

2010

Philosophical Magazine

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. Interaction of a moving 101-2 twin boundary with perfect dislocations and loops in an HCP metal. Philosophical Magazine, Taylor & Francis, 2010, 90 (07-08) AbstractAtomic-scale computer simulation is used to investigate the interaction of a moving twin boundary in an HCP metal with either a straight 1/3 dislocation lying perpendicular to the direction of twinning shear or a periodic row of perfect dislocation loops. The screw dislocation does not decompose in the moving interface and has no effect on its motion. The 60° mixed dislocation is attracted by the boundary and decomposes into twinning dislocations and a disconnection (an interfacial defect with both step and dislocation character): the sign of the crystal dislocation determines the form of the disconnection and thus its effect on twin boundary motion.Boundary reactions with crystal dislocations are likely to be important for assisting the twinning process. Loops with Burgers vector, b, parallel to the interface are reformed in the other crystal after the twin boundary has passed through. The boundary attracts both interstitial and vacancy dislocation loops with inclined b but is not transparent to them, for the complete loop is swept along its glide prism by the moving interface.Depending on its nature, a loop either retains its structure in its parent crystal or is absorbed in the interface. The decomposition product in the latter case is consistent with the reactions of straight dislocations. The results indicate that twinning is efficient at sweeping loops from the microstructure when their density is low and is suppressed by loops when their density is high.

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Section: Discussionsupporting

confidence: 79%

Section: Modelmentioning

confidence: 99%

Section: Modelmentioning

confidence: 99%

“…They move with the twin boundary by conservative climb along their riser [5,16], thereby supplying the twinning disconnections necessary to keep the boundary moving.…”

Section: Modelmentioning

confidence: 99%

mentioning

confidence: 99%

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Interaction of a moving { } twin boundary with perfect dislocations and loops in a hcp metal

Serra

Bacon

2010

Philosophical Magazine

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Atomic Computer Simulation: Large Scale Calculations of Defect Properties by Empirical Potentials

Serra

2001

phys. stat. sol. (b)

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Atomic Structure of Extended Defects in Wurtzite GaN Epitaxial Layers

Ruterana

Nouet

2001

phys. stat. sol. (b)

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Using high resolution electron microscopy, atomistic modelling and image simulations, typical contrast was identified for most of the extended defects which form in epitaxial GaN layers. There are three types of defects which propagate into the active layers: the threading dislocations, prismatic stacking faults and inversion domains. The atomic structure of the a pure edge threading dislocations was shown to exhibit 5/7, or 8 atom cycles. The two configurations were observed at a similar frequency for isolated dislocations and low angle grain boundaries. Coincidence grain boundaries were studied and they were made of pure edge a dislocations with the above identified atomic structures. A topological analysis of high angle grain boundaries was carried out in order to determine the defect content at the interfaces. The reconstruction of some boundaries was only possible by taking into account the occurrence of structural units which exhibit 4 atom ring cycles for the dislocation cores. The f1 2 210g stacking fault has two atomic configurations in wurtzite (Ga, Al, In)N with 1/2 h10 1 11i and 1/6 h20 2 23i displacement vectors. It originates from steps at the SiC surface and it can form on a flat (0001) sapphire surface. The two atomic configurations have comparable energy in AlN, whereas the 1/2 h10 1 11if1 2 210g atomic configuration should be more stable in GaN and InN. Observations carried out in plan-view show the 1/2 h10 1 11if1 2 210g atomic configuration in GaN layers. The 1/6 h20 2 23i configuration was found inside the AlN buffer layer in cross section observations. It folds rapidly to the basal plane, and when back into the prismatic plane, it bears the 1/2 h10 1 11if1 2 210g atomic configuration. The f10 1 10g inversion domains in GaN layers grown on sapphire substrate were identified in multi-beam dark field images and by convergent beam electron diffraction. In the investigated samples, Holt and V models are shown to form in samples depending on the growth conditions. The samples containing Holt inversion domains exhibited a flat surface morphology, whereas the V IDBs were observed in the centre of small pyramids (100 nm high) protruding at the sample surface. The Holt inversion domains were always smaller (< 20 nm), at quite high densities (2.5 Â 10 10 cm --2 ), whereas the V ones could reach 50 nm and one order of magnitude lower density. The inversion domains were found to be generated mostly at sapphire surface steps where they minimized the large misfit along the c axis (20%).

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A new model for {1012} twin growth in hcp metals

Cited by 240 publications

References 14 publications

Interaction of a moving { } twin boundary with perfect dislocations and loops in a hcp metal

Interaction of a moving { } twin boundary with perfect dislocations and loops in a hcp metal

Atomic Computer Simulation: Large Scale Calculations of Defect Properties by Empirical Potentials

Atomic Structure of Extended Defects in Wurtzite GaN Epitaxial Layers

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