Dislocation Structure of Cu/Nu (100) Semi-Coherent Interface and Its Role in Lattice Dislocation Nucleation

Atomistic simulation studies of dislocation nucleation and propagation in nanoscale multilayered metallic systems (Cu-Ni and Cu-Nb) are performed. Nanoindentation model is used to generate dislocations at and near the surface. Interaction of the propagating dislocations with two types of interfaces (coherent and incoherent) is analyzed. In the case of coherent interface, Cu(111)-Ni(111), dislocations that initiate in Cu layer propagate through the interface into Ni. However, the interface acts as an obstacle for dislocation propagation and leads to a higher dislocation density near the interface. In the case of incoherent interface, Cu(111)-Nb(110), dislocations that initiate in Cu do not propagate into Nb and tend to accumulate in copper near the interface. In both cases, the interfaces provide mechanisms for strengthening the nanoscale multilayered metallic systems.

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Grain Boundary Dislocation Structure and Motion in an Aluminum Σ=3 Bicrystal

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100164106 ◽

1996 ◽

Vol 54 ◽

pp. 328-329

Author(s):

D. L. Medlin ◽

S.M. Foiles ◽

C. Barry Carter

Keyword(s):

Grain Boundary ◽

Rigid Body ◽

Twin Boundary ◽

Dislocation Structure ◽

Lattice Dislocation ◽

Boundary Dislocation ◽

Perfect Lattice ◽

Structure And Motion ◽

Rigid Body Displacement ◽

Image Position

A lattice dislocation may interact with a grain boundary leaving either a residual dislocation or a step or both. These products may then contribute to further deformation by themselves moving along the interfaces. For instance, Pond1 observed the dissociation of a perfect lattice dislocation in an aluminum Σ=3 (211) incoherent twin boundary by a reaction of the type:Furthermore, the a/3[111] dislocation was observed to dissociate into two partial grain boundary dislocations (GBD), with Burgers vectors of approximately 2a/9[111] and a/9[111], separating structurally degenerate regions of opposite rigid body displacement.

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Effects of solutes on dislocation nucleation and interface sliding of bimetal semi-coherent interface

International Journal of Plasticity ◽

10.1016/j.ijplas.2020.102725 ◽

2020 ◽

Vol 131 ◽

pp. 102725

Author(s):

C.J. Wang ◽

B.N. Yao ◽

Z.R. Liu ◽

X.F. Kong ◽

D. Legut ◽

...

Keyword(s):

Dislocation Nucleation ◽

Coherent Interface ◽

Interface Sliding

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The dislocation structure of a 10° [110] tilt boundary in silicon

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100074446 ◽

1983 ◽

Vol 41 ◽

pp. 114-115

Author(s):

B. Cunningham ◽

D.G. Ast

Keyword(s):

Dislocation Structure ◽

Tilt Angle ◽

Imaging Technique ◽

Diamond Lattice ◽

Tilt Boundary ◽

Formation Mechanisms ◽

Diffraction Contrast ◽

Lattice Fringe ◽

Tilt Boundaries ◽

Chemically Vapor Deposited

There have Been a number of studies of low-angle, θ < 4°, [10] tilt boundaries in the diamond lattice. Dislocations with Burgers vectors a/2<110>, a/2<112>, a<111> and a<001> have been reported in melt-grown bicrystals of germanium, and dislocations with Burgers vectors a<001> and a/2<112> have been reported in hot-pressed bicrystals of silicon. Most of the dislocations were found to be dissociated, the dissociation widths being dependent on the tilt angle. Possible dissociation schemes and formation mechanisms for the a<001> and a<111> dislocations from the interaction of lattice dislocations have recently been given.The present study reports on the dislocation structure of a 10° [10] tilt boundary in chemically vapor deposited silicon. The dislocations in the boundary were spaced about 1-3nm apart, making them difficult to resolve by conventional diffraction contrast techniques. The dislocation structure was therefore studied by the lattice-fringe imaging technique.

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Mechanical Properties and Dislocation Structure of Single Crystal Cdte Deformed in Compression at 300°C

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010009292x ◽

1976 ◽

Vol 34 ◽

pp. 592-593

Author(s):

Ernest L. Hall ◽

J. B. Vander Sande

Keyword(s):

Mechanical Properties ◽

Single Crystal ◽

Dislocation Structure ◽

Room Temperature ◽

Elevated Temperatures ◽

Strain Curve ◽

Optical Devices ◽

Semiconductor Compound ◽

Wide Range ◽

Sample Orientation

The present paper describes research on the mechanical properties and related dislocation structure of CdTe, a II-VI semiconductor compound with a wide range of uses in electrical and optical devices. At room temperature CdTe exhibits little plasticity and at the same time relatively low strength and hardness. The mechanical behavior of CdTe was examined at elevated temperatures with the goal of understanding plastic flow in this material and eventually improving the room temperature properties. Several samples of single crystal CdTe of identical size and crystallographic orientation were deformed in compression at 300°C to various levels of total strain. A resolved shear stress vs. compressive glide strain curve (Figure la) was derived from the results of the tests and the knowledge of the sample orientation.

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HREM observation of dislocations near room temperature fractures in silicon

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100106521 ◽

1988 ◽

Vol 46 ◽

pp. 892-893

Author(s):

M. H. Rhee ◽

W. A. Coghlan

Keyword(s):

Cross Section ◽

Room Temperature ◽

Single Crystal Silicon ◽

Dislocation Nucleation ◽

Back Side ◽

Ion Milling ◽

Crystal Silicon ◽

Flat Surfaces ◽

Induced Fractures ◽

Vicker’S Microhardness

Silicon is believed to be an almost perfectly brittle material with cleavage occurring on {111} planes. In such a material at room temperature cleavage is expected to occur prior to any dislocation nucleation. This behavior suggests that cleavage fracture may be used to produce usable flat surfaces. Attempts to show this have failed. Such fractures produced in semiconductor silicon tend to occur on planes of variable orientation resulting in surfaces with a poor surface finish. In order to learn more about the mechanisms involved in fracture of silicon we began a HREM study of hardness indent induced fractures in thin samples of oxidized silicon.Samples of single crystal silicon were oxidized in air for 100 hours at 1000°C. Two pieces of this material were glued together and 500 μm thick cross-section samples were cut from the combined piece. The cross-section samples were indented using a Vicker's microhardness tester to produce cracks. The cracks in the samples were preserved by thinning from the back side using a combination of mechanical grinding and ion milling.

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Observations of dislocation interactions with recrystallized grain boundaries

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100105205 ◽

1988 ◽

Vol 46 ◽

pp. 628-629

Author(s):

C. W. Price

Keyword(s):

Dislocation Density ◽

Grain Boundary ◽

Strain Rate ◽

Grain Boundaries ◽

Dislocation Structure ◽

Hot Deformation ◽

Static Recrystallization ◽

High Dislocation Density ◽

High Angle ◽

Dislocation Interactions

Little evidence exists on the interaction of individual dislocations with recrystallized grain boundaries, primarily because of the severely overlapping contrast of the high dislocation density usually present during recrystallization. Interesting evidence of such interaction, Fig. 1, was discovered during examination of some old work on the hot deformation of Al-4.64 Cu. The specimen was deformed in a programmable thermomechanical instrument at 527 C and a strain rate of 25 cm/cm/s to a strain of 0.7. Static recrystallization occurred during a post anneal of 23 s also at 527 C. The figure shows evidence of dissociation of a subboundary at an intersection with a recrystallized high-angle grain boundary. At least one set of dislocations appears to be out of contrast in Fig. 1, and a grainboundary precipitate also is visible. Unfortunately, only subgrain sizes were of interest at the time the micrograph was recorded, and no attempt was made to analyze the dislocation structure.

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Bright field and weak-beam images of dislocations gliding on (001) planes in F.C.C. metals

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100108908 ◽

1978 ◽

Vol 36 (1) ◽

pp. 352-353

Author(s):

H. P. Karnthaler ◽

A. Korner

Keyword(s):

Single Crystals ◽

Dislocation Structure ◽

Room Temperature ◽

Stage Ii ◽

Bright Field ◽

Weak Beam ◽

Standard Orientation

In f.c.c. metals slip is observed to occur generally on {111} planes. Glide dislocations on intersecting {111} planes can react with each other and form Lomer-Cottrell locks which lie along a <110> direction and are sessile since they are split on two {111} planes. Cottrell already pointed out that these dislocations could glide on {001} planes if they were not split. The first study of this phenomenon has been published recently. It is the purpose of this paper to report some interesting new details of the dislocations gliding on {001} planes in pure Ni, Cu, and Ag deformed at room temperature.Single crystals are grown with standard orientation and strained into stage II. The crystals are sliced parallel to the (001) planes. The dislocation structure is studied by TEM and the Burgers vectors ḇ and glide planes of the dislocations are determined unambiguously.In Fig.l primary P and secondary S dislocations react and form composite dislocations K.

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