The Observations on Faulted Dipoles in Deformed Tial—Based Alloys

1994 ◽  
Vol 364 ◽  
Author(s):  
Y. Gao ◽  
J. Zhu ◽  
Q. G. Cai
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Plastic Deformation ◽  
Low Temperature ◽  
Deformation Temperature ◽  
Room Temperature ◽  
Single Phase ◽  
Deformation Structure ◽  
Partial Dislocations ◽  
Transmission Electron

AbstractThe deformation structure of polycrystalline TiAl-based alloys after uniaxial compression at temperature range from 77K to 1073K has been examined using transmission electron microscopy. It was observed that a large number of faulted dipoles are commonly present in deformation structure of the alloys compressed at low temperature 77K and room temperature. The nature of the faulted dipoles has been determined to be intrinsic stacking fault lying on {111} plane, bounded by 1/6<112] partial dislocations. A possible mechanism for the formation of the faulted dipoles was suggested. The results of the statistic observation shows that faulted dipoles in deformed Ti-48A1 and Ti-(47–48) Al-X (X = V,Cr,Mn) alloys are less than those in single phase Ti-52A1 alloy, and the number of the faulted dipoles decreases with increasing deformation temperature. The effect of the faulted dipoles on plastic deformation of the alloy was discussed.

scholarly journals In situ environmental HRTEM discloses low temperature carbon soot oxidation by ceria–zirconia at the nanoscale

2019 ◽  
Vol 55 (27) ◽  
pp. 3876-3878 ◽  
Author(s):  
Eleonora Aneggi ◽  
Jordi Llorca ◽  
Alessandro Trovarelli ◽  
Mimoun Aouine ◽  
Philippe Vernoux
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Low Temperature ◽  
Room Temperature ◽  
Soot Oxidation ◽  
Environmental Transmission ◽  
Transmission Electron ◽  
Carbon Soot ◽  
Environmental Transmission Electron Microscopy

In situ environmental transmission electron microscopy discloses room temperature carbon soot oxidation by ceria–zirconia at the nanoscale.

scholarly journals A single iron site confined in a graphene matrix for the catalytic oxidation of benzene at room temperature

2015 ◽  
Vol 1 (11) ◽  
pp. e1500462 ◽  
Author(s):  
Dehui Deng ◽  
Xiaoqi Chen ◽  
Liang Yu ◽  
Xing Wu ◽  
Qingfei Liu ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Low Temperature ◽  
Catalytic Oxidation ◽  
Room Temperature ◽  
Single Atom ◽  
Intermediate Structure ◽  
Oxidation Reactions ◽  
Transmission Electron ◽  
Oxidation Of Benzene

Coordinatively unsaturated (CUS) iron sites are highly active in catalytic oxidation reactions; however, maintaining the CUS structure of iron during heterogeneous catalytic reactions is a great challenge. Here, we report a strategy to stabilize single-atom CUS iron sites by embedding highly dispersed FeN4 centers in the graphene matrix. The atomic structure of FeN4 centers in graphene was revealed for the first time by combining high-resolution transmission electron microscopy/high-angle annular dark-field scanning transmission electron microscopy with low-temperature scanning tunneling microscopy. These confined single-atom iron sites exhibit high performance in the direct catalytic oxidation of benzene to phenol at room temperature, with a conversion of 23.4% and a yield of 18.7%, and can even proceed efficiently at 0°C with a phenol yield of 8.3% after 24 hours. Both experimental measurements and density functional theory calculations indicate that the formation of the Fe═O intermediate structure is a key step to promoting the conversion of benzene to phenol. These findings could pave the way toward highly efficient nonprecious catalysts for low-temperature oxidation reactions in heterogeneous catalysis and electrocatalysis.

Microstructure and Indentation Fracture of Dysprosium Niobate

2005 ◽  
Vol 20 (6) ◽  
pp. 1422-1427 ◽  
Author(s):  
Byong-Taek Lee ◽  
Waltraud M. Kriven
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Plastic Deformation ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Indentation Fracture ◽  
Optical Scanning ◽  
Periodic Arrays ◽  
Transmission Electron ◽  
Hot Hardness

The high-temperature indentation fracture and microstructures of dysprosium niobate (DyNbO4) were investigated by optical, scanning, and transmission electron microscopy (OM, SEM, and TEM). Polycrystalline samples were sintered at 1350 °C for 3 h and cut into 3 mm disks for TEM. The disks were indented in a Nikon QM (Tokyo, Japan) hot hardness indenter at room temperature up to 1000 °C. Many lamellar twins having different widths were observed by TEM as well as intergranular microcracks. The room temperature hardness was relatively low at 5.64 GPa and decreased with elevated temperatures. Crack lengths were short, showing a typical micro-cracking effect. In the sample indented at 1000 °C, dislocations in periodic arrays were evident, and their density increased markedly due to heavy plastic deformation.

DIELECTRIC PROPERTIES OF ULTRAFINE Zn-DOPED CaCu3Ti4O12 CERAMIC

2012 ◽  
Vol 02 (01) ◽  
pp. 1250007 ◽  
Author(s):  
LAXMAN SINGH ◽  
U. S. RAI ◽  
K. D. MANDAL ◽  
MADHU YASHPAL
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Room Temperature ◽  
Single Phase ◽  
Average Particle Size ◽  
Average Particle ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Sintered Powder

Ultrafine powder of CaCu2.80Zn0.20Ti4O12 ceramic was prepared using a novel semi-wet method. DTA/TG analysis of dry powder gives pre-information about formation of final product around 800°C. The formation of single phase was confirmed by X-ray diffraction analysis. The average particle size of sintered powder of the ceramic obtained from XRD and Transmission electron microscopy was found 59 nm and 102 nm, respectively. Energy Dispersive X-ray studies confirm the stoichiometry of the synthesized ceramic. Dielectric constant of the ceramic was found to be 2617 at room temperature at 1 kHz.

Transmission electron microscope investigation of indentation induced dislocation configurations on the (001) GaSb face

1994 ◽  
Vol 209 (3) ◽  
Author(s):  
J. Doerschel
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Microscope ◽  
Transmission Electron Microscope ◽  
Room Temperature ◽  
Stacking Faults ◽  
Electron Microscope Investigation ◽  
Partial Dislocations ◽  
Transmission Electron ◽  
Induced Dislocation

AbstractDislocation configurations induced by room temperature microindentations on the (001) face of GaSb (undoped and Te-doped) have been studied using high voltage transmission electron microscopy. Perfect and partial dislocations could be found in all four arms of the dislocation rosette around the indent. Microtwins and rarely single stacking faults are associated with the partials. Contrary to other binary III–V compounds, an “inverse” glide prism along the [1[unk]0]/[[unk]10] rosette arms is created and it is bounded by {111}

Deformation of the Orthorhombic Phase in Ti-Al-Nb Alloys

1990 ◽  
Vol 213 ◽  
Author(s):  
D. Banerjee ◽  
R.G. Rowe ◽  
E.L. Hall
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Plastic Deformation ◽  
Orthorhombic Phase ◽  
Deformation Structure ◽  
Transmission Electron ◽  
Slip Planes ◽  
Dislocation Dissociation

ABSTRACTThe deformation structure of the alpha-2 and orthorhombic phase in two alloys of the Ti-Al-Nb system has been characterised by transmission electron microscopy after plastic deformation of about 2% in compression at room temperauture. The orthorhombic phase is shown to deform by all slip modes present in the alpha-2 phase. In addition, extensive “c” component slip is observed in the orthorhombic phase on slip planes that are not equivalent to those observed for “c”component slip in alpha-2. Dislocation dissociation on both basal and prismatic planes of dislocations without a c component is observed in both phases.

Scanning and Transmission Electron Microscopy of Human Red Blood Cells

1969 ◽  
Vol 27 ◽  
pp. 44-45
Author(s):  
A.J. Tousimis ◽  
T.R. Padden
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Blood Cells ◽  
Room Temperature ◽  
Type Specimen ◽  
New Combination ◽  
Human Red Blood Cells ◽  
Transmission Electron ◽  
Microscope Slides ◽  
Scanning Electron

The size, shape and surface morphology of human erythrocytes (RBC) were examined by scanning electron microscopy (SEM), of the fixed material directly and by transmission electron microscopy (TEM) of surface replicas to compare the relative merits of these two observational procedures for this type specimen.A sample of human blood was fixed in glutaraldehyde and washed in distilled water by centrifugation. The washed RBC's were spread on freshly cleaved mica and on aluminum coated microscope slides and then air dried at room temperature. The SEM specimens were rotary coated with 150Å of 60:40- gold:palladium alloy in a vacuum evaporator using a new combination spinning and tilting device. The TEM specimens were preshadowed with platinum and then rotary coated with carbon in the same device. After stripping the RBC-Pt-C composite film, the RBC's were dissolved in 2.5N HNO3 followed by 0.2N NaOH leaving the preshadowed surface replicas showing positive topography.

Formation of Dislocation Channels in Neutron Irradiated Molybdenum

1972 ◽  
Vol 30 ◽  
pp. 672-673
Author(s):  
S. Mahajan
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Ambient Temperature ◽  
Room Temperature ◽  
Channel Formation ◽  
Early Stages ◽  
Transmission Electron ◽  
Three Stages ◽  
Two Stages ◽  
Polycrystalline Molybdenum

The evolution of dislocation channels in irradiated metals during deformation can be envisaged to occur in three stages: (i) formation of embryonic cluster free regions, (ii) growth of these regions into microscopically observable channels and (iii) termination of their growth due to the accumulation of dislocation damage. The first two stages are particularly intriguing, and we have attempted to follow the early stages of channel formation in polycrystalline molybdenum, irradiated to 5×1019 n. cm−2 (E > 1 Mev) at the reactor ambient temperature (∼ 60°C), using transmission electron microscopy. The irradiated samples were strained, at room temperature, up to the macroscopic yield point.Figure 1 illustrates the early stages of channel formation. The observations suggest that the cluster free regions, such as A, B and C, form in isolated packets, which could subsequently link-up to evolve a channel.

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