Atomistic simulations and Peierls–Nabarro analysis of the Shockley partial dislocations in palladium

1999 ◽  
Vol 15 (3) ◽  
pp. 367-379 ◽  
Author(s):  
Björn von Sydow ◽  
Jan Hartford ◽  
Göran Wahnström
Keyword(s):  
Atomistic Simulations ◽  
Shockley Partial ◽  
Partial Dislocations

Extended Defects in 4H-SiC PiN Diodes

2002 ◽  
Vol 742 ◽  
Author(s):  
M. E. Twigg ◽  
R. E. Stahlbush ◽  
M. Fatemi ◽  
S. D. Arthur ◽  
J. B. Fedison ◽  
...  
Keyword(s):  
Elevated Temperatures ◽  
Compressive Strain ◽  
Pin Diode ◽  
Extended Defects ◽  
Pin Diodes ◽  
Plan View ◽  
Shockley Partial ◽  
Inhomogeneous Strain ◽  
Partial Dislocations ◽  
Transmission Electron

ABSTRACTUsing site-specific plan-view transmission electron microscopy (TEM) and lightemission imaging (LEI), we have identified SFs formed during forward biasing of 4H-SiC PiN diodes. These SFs are bounded by Shockley partial dislocations and are formed by shear strain rather than by condensation of vacancies or interstitials. Detailed analysis using TEM diffraction contrast experiments reveal SFs with leading carbon-core Shockley partial dislocations as well as with the silicon-core partial dislocations observed in plastic deformation of 4H-SiC at elevated temperatures. The leading Shockley partials are seen to relieve both tensile and compressive strain during PiN diode operation, suggesting the presence of a complex and inhomogeneous strain field in the 4H-SiC layer.

Recombination of Shockley partial dislocations by electron beam irradiation in wurtzite GaN

2019 ◽  
Vol 126 (16) ◽  
pp. 165702 ◽  
Author(s):  
I. Belabbas ◽  
I. G. Vasileiadis ◽  
J. Moneta ◽  
J. Smalc-Koziorowska ◽  
G. P. Dimitrakopulos
Keyword(s):  
Electron Beam ◽  
Electron Beam Irradiation ◽  
Beam Irradiation ◽  
Shockley Partial ◽  
Partial Dislocations

Effect of Ta on the Structure and Dynamics of γ/α2 Interfaces in Tial

1990 ◽  
Vol 213 ◽  
Author(s):  
S. R. Singh ◽  
J. M. Howe
Keyword(s):  
Partial Dislocation ◽  
Growth Mechanisms ◽  
Tial Alloys ◽  
Shockley Partial ◽  
Structure And Dynamics ◽  
Partial Dislocations ◽  
Α2 Phase ◽  
Atomically Flat ◽  
Ledge Mechanism ◽  
Image Simulations

ABSTRACTThe structure of γ/α interfaces in binary and Ta-containing TiAl alloys were analyzed by HRTEM and image simulations. Growth of α2 was found to be due to a ledge mechanism, consisting of Shockley partial dislocations on alternate (111)γ planes. The interface is atomically flat between the ledges and addition of Ta was found to transform arrays of growth ledges in the binary alloy into islands on the plate faces in the Ta-containing alloy. These islands of α2 on the γ/α2 interfaces were 4–7nm wide and increased in size with decreasing ageing temperature. The height of the ledges and islands were always a multiple of the c-parameter (0.46nm) of the α2 phase. The islands were bounded by 90°(edge) and 30° screw) Shockley partial dislocations. The 30° partial dislocation cores were localized whereas the 90° partial dislocation cores appeared to be highly delocalized due to presence of a high density of kinks, which in one case was found to be about 0.65nm−1.These results are interpreted in terms of the growth mechanisms and morphology of the α2 phase.

Atomistic simulation of fracture in Ni3Al

2008 ◽  
Vol 23 (6) ◽  
pp. 1597-1603 ◽  
Author(s):  
Hong-Xian Xie ◽  
Chong-Yu Wang ◽  
Tao Yu
Keyword(s):  
Atomistic Simulation ◽  
Crack Tip ◽  
Dislocation Core ◽  
Atomic Configuration ◽  
Close Attention ◽  
Shockley Partial ◽  
Simulation Process ◽  
Partial Dislocations ◽  
Higher Temperature ◽  
Dynamics Method

The molecular dynamics method has been used to simulate mode I cracking in Ni3Al. Close attention has been paid to the process of atomic configuration evolution of the cracks. The simulation results show that at low temperature, the Shockley partial dislocations are emitted before the initiation of the crack propagation, subsequently forming the pseudo-twins on (111) planes in crack-tip zone, and then the crack cleavage occurs. The emitting of the Shockley partial dislocations accompanies the crack cleavage during the simulation process. At the higher temperature, the blunting at the crack tip is caused by the [110] superdislocations emitted on (100) plane. The present work also shows that the dipole dislocations on (111) planes in the 1/2[110] dislocation core can be formed.

Deformation-induced α2 ↔ γ phase transformation in a Ti–48Al–2Cr alloy

2000 ◽  
Vol 15 (10) ◽  
pp. 2145-2150 ◽  
Author(s):  
J. X. Zhang ◽  
H. Q. Ye
Keyword(s):  
Electron Microscopy ◽  
Phase Transformation ◽  
Lattice Misfit ◽  
Hrem Image ◽  
Shockley Partial ◽  
Partial Dislocations ◽  
Transmission Electron ◽  
Ledge Mechanism ◽  
Related Process ◽  
Image Simulations

The structure of γ–α2 interfaces in deformed Ti–48Al–2Cr alloy was analyzed by high-resolution transmission electron microscopy (HREM) and image simulations. Growth of γ–TiAl plate in α2–Ti3Al phase was found to be a result of a ledge mechanism consisting of Shockley partial dislocations on alternate (0001)α2 planes. The height of the ledges was always a multiple of two (0001)α2 planes. The γ → α2 phase transformation was also an interface-related process. Large ledges of six close packed planes (111)γ high were often observed at the γ–α2 interface. Every large ledge consisted of six Shockley partial dislocations that originated from the γ–a2 interfacial lattice misfit. The movement of these partial dislocations accomplished the transformation of γ → α2 phase. Comparing the experimental and simulated HREM image, it was found that atomic reordering appears during the deformation-induced γ↔α2 transformation.

The Micromechanisms of Deformation in Nanoporous Gold

2009 ◽  
Vol 1224 ◽  
Author(s):  
Rui Dou ◽  
Brian Derby
Keyword(s):  
Nanoporous Gold ◽  
Compression Testing ◽  
Shockley Partial ◽  
Deformation Structures ◽  
Partial Dislocations ◽  
Dislocation Densities ◽  
Very High

AbstractWe have carried out a TEM investigation of the micromechanisms of deformation in these nanoporous gold specimens after compression testing. We find that the nanoporous specimens show deformation localised to the nodes between the ligaments of the foamed structure, with very high densities of microtwins and Shockley partial dislocations in these regions. These deformation structures are very different from those seen after solid nanowires are tested in compression, which show very low dislocation densities and a few sparsely distributed twins. However, similar dislocation structures to those found in the nanoporous specimens are observed in the larger nanowires when they are deformed in bending. The currently accepted model for the deformation of nanoporous gold, implicitly assumes that the deformation of these structures is by bending near the nodes where ligaments intersect. We hypothesis that the much higher dislocation densities seen in both the nanoporous gold and the nanowires deformed in bending are evidence for the presence of geometrically necessary dislocations in these deformed structures.

scholarly journals Size-induced twinning in InSb semiconductor during room temperature deformation

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Florent Mignerot ◽  
Bouzid Kedjar ◽  
Hadi Bahsoun ◽  
Ludovic Thilly
Keyword(s):  
Strain Rate ◽  
Deformation Mechanism ◽  
Room Temperature ◽  
Activation Volume ◽  
Ion Beam ◽  
Temperature Deformation ◽  
Small Scale ◽  
Shockley Partial ◽  
Partial Dislocations ◽  
Micro Pillars

AbstractRoom-temperature deformation mechanism of InSb micro-pillars has been investigated via a multi-scale experimental approach, where micro-pillars of 2 µm and 5 µm in diameter were first fabricated by focused ion beam (FIB) milling and in situ deformed in the FIB-SEM by micro-compression using a nano-indenter equipped with a flat tip. Strain rate jumps have been performed to determine the strain rate sensitivity coefficient and the related activation volume. The activation volume is found to be of the order of 3–5 b3, considering that plasticity is mediated by Shockley partial dislocations. Transmission electron microscopy (TEM) thin foils were extracted from deformed micro-pillars via the FIB lift-out technique: TEM analysis reveals the presence of nano-twins as major mechanism of plastic deformation, involving Shockley partial dislocations. The presence of twins was never reported in previous studies on the plasticity of bulk InSb: this deformation mechanism is discussed in the context of the plasticity of small-scale samples.

Observation of dislocation reactions in CDTE at lattice resolution

1983 ◽  
Vol 41 ◽  
pp. 112-113
Author(s):  
T. Yamashita ◽  
R. Sinclair
Keyword(s):  
Partial Dislocation ◽  
Video Recording ◽  
Dislocation Motion ◽  
Video Tape ◽  
Exposure Rate ◽  
Shockley Partial Dislocation ◽  
Shockley Partial ◽  
Partial Dislocations ◽  
Lattice Resolution ◽  
Obvious Extension

Recently, lattice resolution video-recording of dislocation motion in CdTe has been reported by Sinclair et al, using the Cambridge 500 keV microscope equipped with a TV camera. Phenomena such as the motion of Shockley partial dislocations and climb of Frank dislocations were recorded onto a video tape which has an exposure rate of 50 half-frames per second. An obvious extension of this work is to study the dislocation reactions. An example of such a reaction which was detected in CdTe is shown in Fig. 1. The micrographs were taken several seconds apart in a JEOL 200CX microscope, and they show dissociation of a Frank dislocation into a Shockley partial dislocation and a Lomer dislocation (ie., a sessile lock).

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