Unusual Rapidity of Electron Beam Transient Tempering

1986 ◽  
Vol 80 ◽  
Author(s):  
Anjum Tauqir ◽  
Peter R. Strutt
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Beam ◽  
Thermal Treatment ◽  
Rapid Solidification ◽  
High Speed ◽  
Defect Cluster ◽  
High Concentration ◽  
Transmission Electron ◽  
Nucleation Sites

AbstractElectron beam rapid solidification of molybdenum-base high speed steels results in quenched-in metastable phases containing a high concentration of alloying elements. Thermal reprocessing of such material by momentary interaction with the electron beam results in decomposition of martensite at a rate ≈ 100 times faster than that occurring during conventional thermal treatment. It is postulated that this arises from a high concentration of 'defect cluster nucleation sites' during the rapid up-quenching. The product of short thermal treatment is a dispersion of 2–5 nm very fine precipitates identified using transmission electron microscopy as MC type carbides.

Nanoseconds Double-Frame and Streak Transmission Electron Microscopy

1990 ◽  
Vol 48 (1) ◽  
pp. 180-181 ◽  
Author(s):  
Oleg Bostanjoglo ◽  
Jochen Kornitzky
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Beam ◽  
Laser Radiation ◽  
High Speed ◽  
Ccd Camera ◽  
Transmission Electron ◽  
Film Specimen ◽  
532 Nm ◽  
Modern Tool

Material processing and synthesis is increasingly done by lasers. In order to apply this modern tool effectively, the laser-induced physical processes must be well known. As transmission electron microscopy is a powerful method to study the structure of the treated material, it seemed worthwhile to extend this technique for fast phase transitions, as are triggered by laser radiation. High-speed TEM may be realized either by pulsing the detector /l/ or the illuminating electron beam. The latter technique is more convenient and is described here.Fig. 1 shows a high-speed TEM designed for taking either double frame images (exposure/ repetition times ≿ 10 ns/≿ 50 ns) or streak images of transitions induced by a laser in the thin film specimen. It consists of a modified commercial TEM, an attached Q-switched (FWHM 50 ns), frequency-doubled (532 nm) Nd:YAG laser for treating the specimen, and electronics for electron beam pulsing and image storage. The TEM is equipped with focusing/deflecting optics for the laser radiation, an electron beam pulser generating either the exposure times for double frame pictures or the streak, and an image shifter. The image detector is a proximity focusing double stage MicroChannel Plate (MCP)/scintillator assembly. A CCD camera transfers the image to a PC-backed digitizing and frame grabbing card. The components are synchronized by a specially designed logic unit /2/.

Techniques for Transmission Electron Microscopy of Fiber-Matrix Interfaces in Aluminum Alloy-Boron Composites by Ion Erosio

1971 ◽  
Vol 29 ◽  
pp. 204-205
Author(s):  
G. G. Shaw
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Aluminum Alloy ◽  
Electron Beam ◽  
Pure Aluminum ◽  
Ion Milling ◽  
Transmission Electron ◽  
Fiber Matrix ◽  
Ion Erosion ◽  
Row Of Fibers

The morphology and composition of the fiber-matrix interface can best be studied by transmission electron microscopy and electron diffraction. For some composites satisfactory samples can be prepared by electropolishing. For others such as aluminum alloy-boron composites ion erosion is necessary.When one wishes to examine a specimen with the electron beam perpendicular to the fiber, preparation is as follows: A 1/8 in. disk is cut from the sample with a cylindrical tool by spark machining. Thin slices, 5 mils thick, containing one row of fibers, are then, spark-machined from the disk. After spark machining, the slice is carefully polished with diamond paste until the row of fibers is exposed on each side, as shown in Figure 1.In the case where examination is desired with the electron beam parallel to the fiber, preparation is as follows: Experimental composites are usually 50 mils or less in thickness so an auxiliary holder is necessary during ion milling and for easy transfer to the electron microscope. This holder is pure aluminum sheet, 3 mils thick.

Effects of High-Energy Ions on Synthetic Quartz

1972 ◽  
Vol 30 ◽  
pp. 544-545
Author(s):  
Joseph J. Comer ◽  
Charles Bergeron ◽  
Lester F. Lowe
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Beam ◽  
High Energy ◽  
Transmission Electron ◽  
Kikuchi Lines ◽  
High Energy Ions ◽  
Diffraction Patterns ◽  
Dauphiné Twinning ◽  
Beam Damage

Using a Van De Graaff Accelerator thinned specimens were subjected to bombardment by 3 MeV N+ ions to fluences ranging from 4x1013 to 2x1016 ions/cm2. They were then examined by transmission electron microscopy and reflection electron diffraction using a 100 KV electron beam.At the lowest fluence of 4x1013 ions/cm2 diffraction patterns of the specimens contained Kikuchi lines which appeared somewhat broader and more diffuse than those obtained on unirradiated material. No damage could be detected by transmission electron microscopy in unannealed specimens. However, Dauphiné twinning was particularly pronounced after heating to 665°C for one hour and cooling to room temperature. The twins, seen in Fig. 1, were often less than .25 μm in size, smaller than those formed in unirradiated material and present in greater number. The results are in agreement with earlier observations on the effect of electron beam damage on Dauphiné twinning.

The use of an energy-filtering electron microscope to reduce chromatic aberration in images of thick biological specimens

1986 ◽  
Vol 44 ◽  
pp. 88-91
Author(s):  
L. D. Peachey ◽  
J. P. Heath ◽  
G. Lamprecht
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Beam ◽  
Cross Section ◽  
Electron Scattering ◽  
Chromatic Aberration ◽  
Image Resolution ◽  
Incident Electron Energy ◽  
Energy Filtering ◽  
Transmission Electron

Biological specimens of cells and tissues generally are considerably thicker than ideal for high resolution transmission electron microscopy. Actual image resolution achieved is limited by chromatic aberration in the image forming electron lenses combined with significant energy loss in the electron beam due to inelastic scattering in the specimen. Increased accelerating voltages (HVEM, IVEM) have been used to reduce the adverse effects of chromatic aberration by decreasing the electron scattering cross-section of the elements in the specimen and by increasing the incident electron energy.

Transmission electron microscopy studying of structural features of NiTi B2 phase formed under pulsed electron-beam impact

2015 ◽  
Author(s):  
Ludmila L. Meisner ◽  
Alexey A. Neiman ◽  
Alexander I. Lotkov ◽  
Nikolai N. Koval ◽  
Viktor O. Semin ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Beam ◽  
Structural Features ◽  
Pulsed Electron Beam ◽  
Transmission Electron ◽  
B2 Phase
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