Plasticity induced by nanoindentation in a CrCoNi medium-entropy alloy studied by accurate electron channeling contrast imaging revealing dislocation-low angle grain boundary interactions

AbstractWe combine two scanning electron microscopy techniques to investigate the influence of dislocations on the light emission from nitride semiconductors. Combining electron channeling contrast imaging and cathodoluminescence imaging enables both the structural and luminescence properties of a sample to be investigated without structural damage to the sample. The electron channeling contrast image is very sensitive to distortions of the crystal lattice, resulting in individual threading dislocations appearing as spots with black–white contrast. Dislocations giving rise to nonradiative recombination are observed as black spots in the cathodoluminescence image. Comparison of the images from exactly the same micron-scale region of a sample demonstrates a one-to-one correlation between the presence of single threading dislocations and resolved dark spots in the cathodoluminescence image. In addition, we have also obtained an atomic force microscopy image from the same region of the sample, which confirms that both pure edge dislocations and those with a screw component (i.e., screw and mixed dislocations) act as nonradiative recombination centers for the Si-doped c-plane GaN thin film investigated.

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Direct observation of dislocation structure evolution in SRF cavity niobium using electron channeling contrast imaging

Journal of Applied Physics ◽

10.1063/1.5050032 ◽

2018 ◽

Vol 124 (15) ◽

pp. 155105

Author(s):

M. Wang ◽

D. Kang ◽

T. R. Bieler

Keyword(s):

Direct Observation ◽

Dislocation Structure ◽

Structure Evolution ◽

Contrast Imaging ◽

Electron Channeling ◽

Srf Cavity

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Rotational-Electron Channeling Contrast Imaging analysis of dislocation structure in fatigued copper single crystal

Scripta Materialia ◽

10.1016/j.scriptamat.2018.10.050 ◽

2019 ◽

Vol 162 ◽

pp. 103-107 ◽

Cited By ~ 5

Author(s):

G. L'hôte ◽

C. Lafond ◽

P. Steyer ◽

S. Deschanel ◽

T. Douillard ◽

...

Keyword(s):

Single Crystal ◽

Dislocation Structure ◽

Copper Single Crystal ◽

Imaging Analysis ◽

Contrast Imaging ◽

Electron Channeling

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Atomic Scale Analysis of a YSZ Bicrystal Grain Boundary

Microscopy and Microanalysis ◽

10.1017/s1431927600028075 ◽

2001 ◽

Vol 7 (S2) ◽

pp. 400-401

Author(s):

Y. Lei ◽

Y. Ito ◽

N. D. Browning

Keyword(s):

Grain Boundary ◽

Grain Boundaries ◽

Bulk Material ◽

Atomic Scale ◽

Structure Property ◽

Contrast Imaging ◽

Structure Property Relationships ◽

Commercial Applications ◽

Z Contrast ◽

Electron Energy Loss

Yttria-stabilized zirconia (YSZ) has been the subject of many experimental and theoretical studies, due to the commercial applications of zirconia-based ceramics in solid state oxide fuel cells. Since the grain boundaries usually dominate the overall macroscopic performance of the bulk material, it is essential to develop a fundamental understanding of their structure-property relationships. Previous research has been performed on the atomic structure of grain boundaries in YSZ, but no precise atomic scale compositional and chemistry characterization has been carried out. Here we report a detailed analytical study of an [001] symmetric 24° bicrystal tilt grain boundary in YSZ prepared with ∼10 mol % Y2O3 by Shinkosha Co., Ltd by the combination of Z-contrast imaging and electron energy loss spectroscopy (EELS).The experimental analysis of the YSZ sample was carried out on a 200kV Schottky field emission JEOL 201 OF STEM/TEM4.

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Low angle boundary migration of shot‐peened pure nickel investigated by electron channeling contrast imaging and electron backscatter diffraction

Microscopy Research and Technique ◽

10.1002/jemt.23226 ◽

2019 ◽

Vol 82 (6) ◽

pp. 849-855

Author(s):

Jin‐Su Oh ◽

Hyun‐Woo Cha ◽

Tae‐Hoon Kim ◽

Keesam Shin ◽

Cheol‐Woong Yang

Keyword(s):

Electron Backscatter Diffraction ◽

Boundary Migration ◽

Pure Nickel ◽

Contrast Imaging ◽

Electron Channeling ◽

Electron Backscatter ◽

Backscatter Diffraction

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Microcrack Nucleation and Crack Propagation in Equiaxed γ TiAl

MRS Proceedings ◽

10.1557/proc-753-bb3.8 ◽

2002 ◽

Vol 753 ◽

Cited By ~ 1

Author(s):

Martin A. Crimp ◽

Boon-Chi Ng ◽

Benjamin A. Simkin ◽

Thomas R. Bieler

Keyword(s):

Ex Situ ◽

Contrast Imaging ◽

Active Deformation ◽

Electron Channeling ◽

Microcrack Initiation ◽

Grain Orientations ◽

Contrast Analysis ◽

Defect Imaging

ABSTRACTTo gain a better understanding of the ductility limitations in TiAl alloys, the mechanisms involved in deformation strain transfer and/or microcrack initiation at grain boundaries have been examined in an equiaxed near-γ alloy. These studies have been carried out on both in-situ and ex-situ deformed bulk samples using scanning electron microscopy (SEM) techniques for both orientation analysis and deformation defect imaging. Selected area electron channeling patterns (SACPs) have allowed determination of grain orientations, eliminating ambiguity between the a and c axes. Deformation twins and dislocations have been imaged in the bulk samples using electron channeling contrast imaging (ECCI). A combination of ECCI contrast analysis and trace analysis based on orientations determined from SACP has allowed identification of the active deformation systems. Microcracks have been found to initiate at γ-γ boundaries as a result of an inability to adequately transfer twin strain from grain to grain. Once initiated, cracks propagate through cleavage and re-nucleation of grain boundary microcracks in front of the advancing crack. A geometric based predictive factor has been developed that accounts for microcrack initiation at γ-γ boundaries based in deformation twinning and strain accommodation by ordinary dislocations.

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Effect of Grain Boundary Energy Anisotropy on Faceting and Migration of Low Angle Grain Boundaries

Materials Science Forum ◽

10.4028/www.scientific.net/msf.783-786.1634 ◽

2014 ◽

Vol 783-786 ◽

pp. 1634-1639

Author(s):

Dmitri A. Molodov ◽

Jann Erik Brandenburg ◽

Luis Antonio Barrales-Mora ◽

Günter Gottstein

Keyword(s):

Grain Boundary ◽

Grain Boundaries ◽

Elevated Temperatures ◽

Boundary Energy ◽

Migration Behavior ◽

Grain Boundary Energy ◽

Contrast Imaging ◽

Orientation Contrast ◽

And Migration ◽

Twist Boundaries

The faceting and migration behavior of low angle <100> grain boundaries in high purity aluminum bicrystals was investigated. In-situ technique based on orientation contrast imaging was applied. In contrast to the pure tilt boundaries, which remained straight/flat and immobile during annealing at elevated temperatures, mixed tilt-twist boundaries readily assumed a curved shape and steadily moved under the capillary force. Computational analysis revealed that this behavior is due to the inclinational anisotropy of grain boundary energy, which in turn depends on boundary geometry – the energy of pure tilt low angle <100> boundaries is anisotropic, whereas that of mixed tilt-twist boundaries isotropic with respect to boundary inclination.

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