Identification of Cleavage Planes in an Al3Ti-Base Alloy by Electron Channeling in the SEM

1988 ◽  
Vol 133 ◽  
Author(s):  
E. P. George ◽  
W. D. Porter ◽  
D. C. Joy
Keyword(s):  
Electron Beam ◽  
Base Alloy ◽  
Optical Microscope ◽  
Grain Structure ◽  
Cleavage Facet ◽  
Depth Of Focus ◽  
Directionally Solidified ◽  
Electron Channeling ◽  
Equiaxed Grain ◽  
Scanning Electron

ABSTRACTSelected area electron channeling patterns were used to identify the cleavage planes in a polycrystalline Al3Ti-base alloy having the L12 structure. In order to do this unambiguously in the scanning electron microscope (SEM), one needs to know that the cleavage facet from which any given channeling pattern is obtained is indeed normal to the electron beam. We accomplished this by utilizing a recently-developed technique in which an optical microscope with a short depth of focus is inserted in the SEM column and used to measure the elevations of several points on the cleavage facets. By appropriately tilting and rotating the sample, and using the optical microscope to measure elevations, it was possible to orient the facets normal to the beam. The cleavage planes in a cast and extruded alloy having an equiaxed grain structure were compared with those in a directionally-solidified (DS) alloy of the same composition. Of the eight cleavage facets examined in the DS material, six were of the {110} type and two were of the {111} type. Of the six facets examined in the cast and extruded material, two each were of the {110} and {111} types, and one each were of the {100} and {013} types. Although it cannot be said that all possible cleavage planes have been identified in this alloy, the availability of several low-strength cleavage planes apparently exacerbates its brittleness.

Paper 4: Electron Optical Techniques of Failure Investigation

1969 ◽  
Vol 184 (2) ◽  
pp. 25-35 ◽  
Author(s):  
D. Scott ◽  
B. Loy ◽  
R. McCallum ◽  
G. H. Mills
Keyword(s):  
Failure Mechanisms ◽  
Optical Microscope ◽  
Surface Phenomena ◽  
Depth Of Focus ◽  
Optical Techniques ◽  
Fracture Surfaces ◽  
Failure Investigation ◽  
Non Destructive ◽  
Study Of Fracture Surfaces ◽  
Scanning Electron

Fractography, the study of fracture surfaces, is useful in failure investigations as the topography and characteristic markings of such surfaces are indicative of the mechanism of fracture which operated during the initiation of failure and crack propagation. Owing to the low depth of focus of the optical microscope, interpretation of some fracture surfaces may be difficult. The microscopic topography, and its relation to the causes and basic mechanisms of fracture, may be conveniently studied by electron microfractography using non-destructive replica methods. Replicas may be taken from selected areas of the fracture surface of large, unwieldy engineering components. Complementary electron optical techniques such as electron diffraction, scanning electron microscopy, and extraction replicas are used where possible to obtain additional fine-scale information of use in the elucidation of failure mechanisms. An explanation of the various techniques and examples of their use in the work of the National Engineering Laboratory in failure investigations is given. The investigations involve fatigue, brittle fracture, corrosion fatigue, stress corrosion, welding problems, and surface phenomena.

Identification and Characterization of Ultra-Thin (<100 nm) Flakes Using a Combination of Face-Lapping, High Energy (10 kV) SEM Imaging, and TEM

2004 ◽  
Author(s):  
D. Mitro ◽  
S. Subramanian ◽  
S. (Wai Lung) Yeung ◽  
T. Chrastecky ◽  
B. Hagedorn ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Electron Beam ◽  
Oxide Thickness ◽  
High Energy ◽  
Optical Microscope ◽  
Low Energy ◽  
Traditional Procedure ◽  
Sem Imaging ◽  
Scanning Electron

Abstract Ultra-thin (&lt;100 nm) flakes shorting metal lines are difficult to detect and often cause the device to fail after reliability stress or at the customer site. In most cases, the common technique of inspecting the device in an optical microscope followed by conventional low energy (&lt;3.0 kV) scanning electron microscopy (SEM) is often not able to detect this type of defect. In rare cases, where the defect is successfully exposed by the traditional procedure, it is very challenging to perform additional transmission electron microscopy (TEM) characterization of the defect without introducing arifacts during sample preparation of the exposed flake. A new procedure to identify these defects using a combination of face-lapping and high energy (&gt;10 kV) SEM imaging is described in this paper. In this method, the failing device is carefully face-lapped and inspected frequently using a high energy (&gt;10 kV) scanning electron beam. The high energy electron beam penetrates through the oxide layer and detects features embedded below the oxide. This technique greatly incresases the chances of detecting the flake, as the method is capable of detecting the defect at a larger range of oxide thickness as opposed to the traditional method. Additionally, TEM results were improved when the ultra-thin flakes were detected below the surface with the high energy SEM technique. Several examples of ultra-thin flakes found using the high energy SEM vs. low energy SEM will be presented.

Electron Microscopy and X-Ray Microanalysis in Forensic Science

1973 ◽  
Vol 56 (4) ◽  
pp. 930-943
Author(s):  
John L Brown ◽  
James W Johnson
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Chemical Elements ◽  
Optical Microscope ◽  
Forensic Analysis ◽  
Depth Of Focus ◽  
Crystalline Materials ◽  
X Ray ◽  
Transmission Electron ◽  
Scanning Electron

Abstract The optical microscope has long been an important tool in forensic analysis for the comparison of firearms markings and the examination and identification of other minute bits of evidence. The electron microscope permits the examination of even smaller details and offers analytical capabilities unique to the type of instrument used. The transmission electron microscope can be used to identify very small amounts of crystalline materials through the process of electron diffraction. The scanning electron microscope can frequently supersede the optical microscope because of its superior depth of focus and range of magnification. When it is equipped with an energy dispersive X-ray analyzer, most of the chemical elements in a sample can be determined. Applications of these instruments have provided some interesting and instructive results in forensic analysis.

Cleavage fracture in an Al3Ti-based alloy having the Ll2 structure

1989 ◽  
Vol 4 (1) ◽  
pp. 78-84 ◽  
Author(s):  
E. P. George ◽  
W. D. Porter ◽  
H. M. Henson ◽  
W. C. Oliver ◽  
B. F. Oliver
Keyword(s):  
Cleavage Fracture ◽  
Room Temperature ◽  
Optical Microscope ◽  
Objective Lens ◽  
Slip Systems ◽  
Depth Of Focus ◽  
Directionally Solidified ◽  
Transgranular Cleavage ◽  
Three Point Bending ◽  
Cleavage Strength

Selected area electron channeling patterns were used to identify the cleavage planes in a polycrystalline Al–23Ti–6Fe–5V alloy, which is an Al3Ti-based alloy having the Ll2 structure. Alloys like this one are of scientific and technological interest because they fracture by brittle transgranular cleavage, despite the availability of more than five independent slip systems in the Ll2 structure and their relatively low hardness when compared to ductile Ll2 alloys like Ni3Al. Homogenized bars of the levitation zone melted and directionally solidified alloy were fractured at room temperature in three point bending. The fracture surfaces, which consisted almost entirely of brittle transgranular cleavage facets, were examined in a scanning electron microscope (SEM) equipped to take channeling patterns. An optical microscope with a short depth of focus was inserted in the SEM column just below the objective lens, and by focusing it on several points on the cleavage facets, it was possible to orient the facets normal to the optic axis of the SEM prior to taking the channeling patterns. Of the eight cleavage facets examined in this study, six were of the {110} type and two were of the {111} type. Although it cannot be said that these are the only two cleavage planes in this alloy, the availability of more than one plane with low cleavage strength contributes to the brittleness of this alloy. These results are examined in the light of theoretical treatments of cleavage fracture, and comparisons are made with earlier studies on other Ll2 materials.

A comparison of optical microscope- and scanning electron microscope-based cathodoluminescence (CL) imaging and spectroscopy applied to geosciences

2008 ◽  
Vol 72 (4) ◽  
pp. 909-924 ◽  
Author(s):  
J. Götze ◽  
U. Kempe
Keyword(s):  
Electron Beam ◽  
Optical Microscope ◽  
Spectroscopic Studies ◽  
Electron Gun ◽  
Signal Acquisition ◽  
Imaging And Spectroscopy ◽  
Electron Microscopes ◽  
Scanning Electron Microscopes ◽  
Similar Kind ◽  
Scanning Electron

AbstractCathodoluminescence (CL) imaging and spectroscopy are outstanding methods in several fields of geosciences. Cathodoluminescence can be examined using a wide variety of electron-beam equipment. Of special interest to geologists are optical microscopes (OMs) equipped with an electron gun. scanning electron microscopes (SEMs) and electron microprobes. Despite the similar kind of excitation, the results obtained may show marked differences. These are related to the use of focused or defocused as well as a scanned or stationary electron beam and the kind of signal acquisition. Images obtained by OM-CL (hot or cold acceleration) and SEM-CL differ due to different spatial resolution, true colour, grey-scale, or monochromatic detection, contrast inversion, phosphorescence effects, etc.Instrumentation used for spectroscopic studies may differ in sequential or parallel signal acquisition, wavelength range, spectral resolution, and the kind of analytical spot limitation. This is particularly important when investigating transient CL, rare earth element (REE) emissions, or luminescence in the near UV and IR regions as well as samples with small grain sizes and contrasting CL behaviour of adjacent mineral phases.In the present study, the influence of analytical parameters is demonstrated for certain mineral examples including zircon, fluorite, apatite, feldspar, quartz, corundum, kaolinite, and dickite.

scholarly journals Microstructure Modifications and Associated Corrosion Improvements in GH4169 Superalloy Treated by High Current Pulsed Electron Beam

2015 ◽  
Vol 2015 ◽  
pp. 1-5
Author(s):  
Yichang Su ◽  
Guangyu Li ◽  
Liyuan Niu ◽  
Shengzhi Yang ◽  
Jie Cai ◽  
...  
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
Optical Microscope ◽  
High Current ◽  
Pulsed Electron Beam ◽  
Density Of Dislocations ◽  
Nickel Based Superalloy ◽  
Transmission Electron ◽  
Gh4169 Superalloy ◽  
Scanning Electron

The surface of the nickel-based superalloy GH4169 was subjected to high-current pulsed electron beam (HCPEB) treatment. The microstructural morphologies of the material were analysed by means of optical microscope (OP), scanning electron microscope (SEM), and transmission electron microscope (TEM). The results reveal that the irradiated surface was remelted and many craters were formed. The density of craters decreased with the increment of HCPEB pulses. After 20-pulsed HCPEB irradiation, nanostructures were formed in the melted region of the surface. Furthermore, slipping bands and high density of dislocations were also formed due to the severe plastic deformation. The selective purification effect, homogenized composition, nanostructures, and dislocation slips introduced by HCPEB irradiation bring a significant improvement of corrosion resistance of GH4169 superalloy.

Application of Improved Voltage Compensation in the SEM to Imaging of Organic Materials

1973 ◽  
Vol 31 ◽  
pp. 444-445
Author(s):  
P.J. Killingworth ◽  
M. Warren
Keyword(s):  
Electron Beam ◽  
Organic Materials ◽  
Operating Parameters ◽  
Low Density ◽  
Beam Diameter ◽  
Incident Electron Beam ◽  
Specimen Material ◽  
Voltage Compensation ◽  
Selection Of ◽  
Scanning Electron

Ultimate resolution in the scanning electron microscope is determined not only by the diameter of the incident electron beam, but by interaction of that beam with the specimen material. Generally, while minimum beam diameter diminishes with increasing voltage, due to the reduced effect of aberration component and magnetic interference, the excited volume within the sample increases with electron energy. Thus, for any given material and imaging signal, there is an optimum volt age to achieve best resolution.In the case of organic materials, which are in general of low density and electric ally non-conducting; and may in addition be susceptible to radiation and heat damage, the selection of correct operating parameters is extremely critical and is achiev ed by interative adjustment.

Record Wear Studies by Scanning Electron Microscopy

1968 ◽  
Vol 26 ◽  
pp. 364-365
Author(s):  
M.D. Coutts ◽  
E.R. Levin ◽  
J.G. Woodward
Keyword(s):  
Electron Microscopy ◽  
Constant Velocity ◽  
Peak Velocity ◽  
Great Depth ◽  
Depth Of Focus ◽  
Sweep Frequency ◽  
Transmission Electron ◽  
Test Record ◽  
Lateral Mode ◽  
Scanning Electron

While record grooves have been studied by transmission electron microscopy with replica techniques, and by optical microscopy, the former are cumbersome and restricted and the latter limited by lack of depth of focus and resolution at higher magnification. With its great depth of focus and ease in specimen manipulation, the scanning electron microscope is admirably suited for record wear studies.A special RCA sweep frequency test record was used with both lateral and vertical modulation bands. The signal is a repetitive, constant-velocity sweep from 2 to 20 kHz having a duration and repetitive rate of approximately 0.1 sec. and a peak velocity of 5.5 cm/s.A series of different pickups and numbers of plays were used on vinyl records. One centimeter discs were then cut out, mounted and coated with 200 Å of gold to prevent charging during examination. Wear studies were made by taking micrographs of record grooves having 1, 10 and 50 plays with each stylus and comparing with typical “no-play” grooves. Fig. 1 shows unplayed grooves in a vinyl pressing with sweep-frequency modulation in the lateral mode.

X-ray micro tomography in the scanning electron microscope

1978 ◽  
Vol 36 (1) ◽  
pp. 106-107 ◽  
Author(s):  
W. Brünger
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Target Surface ◽  
The Body ◽  
X Rays ◽  
Cross Sectional ◽  
X Ray ◽  
Micro Tomography ◽  
Scanning Electron

Reconstructive tomography is a new technique in diagnostic radiology for imaging cross-sectional planes of the human body /1/. A collimated beam of X-rays is scanned through a thin slice of the body and the transmitted intensity is recorded by a detector giving a linear shadow graph or projection (see fig. 1). Many of these projections at different angles are used to reconstruct the body-layer, usually with the aid of a computer. The picture element size of present tomographic scanners is approximately 1.1 mm2.Micro tomography can be realized using the very fine X-ray source generated by the focused electron beam of a scanning electron microscope (see fig. 2). The translation of the X-ray source is done by a line scan of the electron beam on a polished target surface /2/. Projections at different angles are produced by rotating the object.During the registration of a single scan the electron beam is deflected in one direction only, while both deflections are operating in the display tube.

Micropatterning of Permalloy Films by Electron Lithography

1976 ◽  
Vol 34 ◽  
pp. 448-449
Author(s):  
J. K. Maurin
Keyword(s):  
Electron Beam ◽  
Subsequent Development ◽  
Electron Optical System ◽  
Microelectronic Device ◽  
Magnetic Bubble ◽  
Control Beam ◽  
Photosensitive Material ◽  
Direct Exposure ◽  
Electron Lithography ◽  
Scanning Electron

Conductor, resistor, and dielectric patterns of microelectronic device are usually defined by exposure of a photosensitive material through a mask onto the device with subsequent development of the photoresist and chemical removal of the undesired materials. Standard optical techniques are limited and electron lithography provides several important advantages, including the ability to expose features as small as 1,000 Å, and direct exposure on the wafer with no intermediate mask. This presentation is intended to report how electron lithography was used to define the permalloy patterns which are used to manipulate domains in magnetic bubble memory devices.The electron optical system used in our experiment as shown in Fig. 1 consisted of a high resolution scanning electron microscope, a computer, and a high precision motorized specimen stage. The computer is appropriately interfaced to address the electron beam, control beam exposure, and move the specimen stage.

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