scholarly journals On the Determination of Loop Nature in the Tem

1996 ◽  
Vol 439 ◽  
Author(s):  
M. L. Jenkins ◽  
H. Fukushima ◽  
M. A. Kirk
Keyword(s):  
Ion Irradiation ◽  
Large Fraction ◽  
Reciprocal Lattice ◽  
Direct Methods ◽  
Heavy Ion ◽  
Operating Conditions ◽  
Contrast Analysis ◽  
Small Clusters

AbstractWe have carried out systematic experiments to explore the range of applicability of the two direct methods which are available for the determination of the nature of small clusters. Experiments in heavy-ion irradiated silver and copper, including direct comparisons with the results of Black-White contrast analysis (B-W), forced us to the conclusion that use of the 21/2D technique for the analysis of faulted loops is effectively impossible because of reciprocal-lattice spike and other effects. We used B-W analysis to investigate the nature of the clusters produced by room-temperature heavy-ion irradiation of copper. In-situ irradiations were performed in the Argonne HVEM-Tandem Facility using 40keV and 80keV Kr+ ions. Nearly all of the analysable first-layer loops were found to be vacancy in nature. Some deeper clusters were also certainly vacancy. There is no unequivocal evidence for interstitial loops under these conditions. The near impossibility of establishing that interstitial loops are not present is shown by the fact that a large fraction of loops - over 50% - could not be analysed either because they did not display clear B-W contrast under any condition or sufficiently consistent B-W contrast under several different operating conditions.

Electron and ion irradiation-induced dissolution of mechanical twins in the intermetalic U3Si: An in situ HVEM study

1989 ◽  
Vol 47 ◽  
pp. 652-653
Author(s):  
Charles W. Allen ◽  
Robert C. Birtcher
Keyword(s):  
Elevated Temperatures ◽  
Ion Irradiation ◽  
Ion Beam ◽  
National Laboratory ◽  
Argonne National Laboratory ◽  
Heavy Ion ◽  
High Energy ◽  
Mechanical Twinning ◽  
In Situ Experiments

The uranium silicides, including U3Si, are under study as candidate low enrichment nuclear fuels. Ion beam simulations of the in-reactor behavior of such materials are performed because a similar damage structure can be produced in hours by energetic heavy ions which requires years in actual reactor tests. This contribution treats one aspect of the microstructural behavior of U3Si under high energy electron irradiation and low dose energetic heavy ion irradiation and is based on in situ experiments, performed at the HVEM-Tandem User Facility at Argonne National Laboratory. This Facility interfaces a 2 MV Tandem ion accelerator and a 0.6 MV ion implanter to a 1.2 MeV AEI high voltage electron microscope, which allows a wide variety of in situ ion beam experiments to be performed with simultaneous irradiation and electron microscopy or diffraction.At elevated temperatures, U3Si exhibits the ordered AuCu3 structure. On cooling below 1058 K, the intermetallic transforms, evidently martensitically, to a body-centered tetragonal structure (alternatively, the structure may be described as face-centered tetragonal, which would be fcc except for a 1 pet tetragonal distortion). Mechanical twinning accompanies the transformation; however, diferences between electron diffraction patterns from twinned and non-twinned martensite plates could not be distinguished.

In situ study of defect accumulation in zirconium under heavy ion irradiation

2013 ◽  
Vol 433 (1-3) ◽  
pp. 95-107 ◽  
Author(s):  
Y. Idrees ◽  
Z. Yao ◽  
M.A. Kirk ◽  
M.R. Daymond
Keyword(s):  
Ion Irradiation ◽  
Heavy Ion ◽  
In Situ Study ◽  
Heavy Ion Irradiation ◽  
Defect Accumulation

scholarly journals In situ microstructural evolution in face-centered and body-centered cubic complex concentrated solid-solution alloys under heavy ion irradiation

2020 ◽  
Vol 198 ◽  
pp. 85-99 ◽  
Author(s):  
Calvin Parkin ◽  
Michael Moorehead ◽  
Mohamed Elbakhshwan ◽  
Jing Hu ◽  
Wei-Ying Chen ◽  
...  
Keyword(s):  
Solid Solution ◽  
Microstructural Evolution ◽  
Ion Irradiation ◽  
Heavy Ion ◽  
Body Centered Cubic ◽  
Heavy Ion Irradiation ◽  
Face Centered

Microcrack Nucleation and Crack Propagation in Equiaxed γ TiAl

2002 ◽  
Vol 753 ◽  
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.

Cantilever Beam Stress Measurements During Ion Irradiation

1995 ◽  
Vol 396 ◽  
Author(s):  
A. I. Van Sambeek ◽  
R.S. Averback
Keyword(s):  
Ion Irradiation ◽  
Reference Electrode ◽  
Heavy Ion ◽  
In Situ Stress ◽  
Stress Measurements ◽  
Beam Sample ◽  
Cantilevered Beam ◽  
In Situ Stress Measurements ◽  
Defect Relaxation

AbstractIn-situ stress measurements on single crystal MgO and A1203 have been performed during ion irradiation. A cantilevered beam sample arrangement was used, with the stress in the implanted layer determined from the deflection of the sample as measured by the change in capacitance between the free end of the sample and a reference electrode. Point defect concentrations are obtained by dividing the volume strain by the defect relaxation volume, with saturation values of 0.8 to 1.2% obtained for 1.0 MeV Ne, Ar and Kr irradiations. Defect production is sublinear with dose, with an efficiency of less than 25% compared to Kinchin-Pease predictions. Ionization induced annealing is evaluated with 1.0 MeV He and 1.0 MeV H irradiations following heavy ion irradiation.

scholarly journals In situ TEM study of G-phase precipitates under heavy ion irradiation in CF8 cast austenitic stainless steel

2015 ◽  
Vol 464 ◽  
pp. 185-192 ◽  
Author(s):  
Wei-Ying Chen ◽  
Meimei Li ◽  
Xuan Zhang ◽  
Marquis A. Kirk ◽  
Peter M. Baldo ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Ion Irradiation ◽  
Heavy Ion ◽  
In Situ Tem ◽  
Heavy Ion Irradiation

In-situ transport and microstructural evolution in GaN Schottky diodes and epilayers exposed to swift heavy ion irradiation

2018 ◽  
Vol 123 (16) ◽  
pp. 161539 ◽  
Author(s):  
Ashish Kumar ◽  
R. Singh ◽  
Parmod Kumar ◽  
Udai B. Singh ◽  
K. Asokan ◽  
...  
Keyword(s):  
Microstructural Evolution ◽  
Ion Irradiation ◽  
Schottky Diodes ◽  
Heavy Ion ◽  
Swift Heavy Ion Irradiation ◽  
Heavy Ion Irradiation ◽  
Swift Heavy Ion
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