Publication

Microstructure of ion-irradiated stoichiometric NiAl intermetallic: a comparative image simulation and transmission electron microscopy study

Maximo Pedro Victoria
2002
Journal Articles

Abstract

A comparative image simulation and transmission electron microscopy (TEM) study has been addressed in order to assess whether NiAl intermetallic undergoes a crystalline-to-amorphous transformation directly induced by the cascade. For this purpose, an NiAl single-crystal specimen has been irradiated with 6 MeV nickel ions to 0.1 dpa (maximum) and observed by conventional TEM in weak-beam imaging mode. This work shows that a crystalline-to-amorphous transformation directly induced by the cascade does not occur (absence of amorphous halo). Image simulation reported a defect cluster size of 2.8 nm as compared to a mean value of 3.0 nm measured on the experimental micrograph. The same image simulation study reported a defect cluster density of 1.7 x 10(24) m(-3) whereas a direct measurement from the experimental micrograph indicates 1.4 x 10(23) m(-3), a value about 10 x lower, most probably due to the resolution limit of the technique and also due to the contrast transfer functiori oscillation along the specimen thickness, which might render a fraction of defect clusters invisible.

Official source

https://infoscience.epfl.ch/entities/publication/a997bc5e-225b-41c7-87f2-9b32ebaf4dcd

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Maximo Pedro Victoria
2002
Journal Articles

Abstract

Official source

https://infoscience.epfl.ch/entities/publication/a997bc5e-225b-41c7-87f2-9b32ebaf4dcd

About this result

Related concepts (27)

Transmission electron microscopy

Transmission electron microscopy (TEM) is a microscopy technique in which a beam of electrons is transmitted through a specimen to form an image. The specimen is most often an ultrathin section less than 100 nm thick or a suspension on a grid. An image is formed from the interaction of the electrons with the sample as the beam is transmitted through the specimen. The image is then magnified and focused onto an imaging device, such as a fluorescent screen, a layer of photographic film, or a sensor such as a scintillator attached to a charge-coupled device.

Scanning transmission electron microscopy

A scanning transmission electron microscope (STEM) is a type of transmission electron microscope (TEM). Pronunciation is [stɛm] or [ɛsti:i:ɛm]. As with a conventional transmission electron microscope (CTEM), images are formed by electrons passing through a sufficiently thin specimen. However, unlike CTEM, in STEM the electron beam is focused to a fine spot (with the typical spot size 0.05 – 0.2 nm) which is then scanned over the sample in a raster illumination system constructed so that the sample is illuminated at each point with the beam parallel to the optical axis.

Electron microscope

An electron microscope is a microscope that uses a beam of electrons as a source of illumination. They use electron optics that are analogous to the glass lenses of an optical light microscope. As the wavelength of an electron can be up to 100,000 times shorter than that of visible light, electron microscopes have a higher resolution of about 0.1 nm, which compares to about 200 nm for light microscopes.