bluuebunny/crossref_metadata_2025_split huggingface dataset:
Structure and Plastic Strain Analysis Utilizing Scanning Electron Microscopy
Authors: Schmidt Frederick E. , Lawlev Alan 
Published: June 2020

‘Forming limit’ or ‘instability limit’ diagrams are particularly useful in the processing of sheet materials by deep drawing or stretch forming. The key to the development of these diagrams is a quantitative characterization of the localized state of strain at various stages throughout the forming process. A novel approach has been developed whereby the distortions of a high-resolution grid, i.e. the strain analysis, are accurately monitored by scanning electron microscopy. A concurrent characterization of the associated surface structure is obtained.The grid for strain analysis is produced by a photoresist technique. Any practical grid master pattern may be used; the most useful shapes for the current studies are rectangles, squares, or circles with a resolution to 200 lines per inch. Photoresist emulsion is applied directly to the sheet specimen surface and air cured. The master pattern is then held secure against the emulsion by vacuum and the composite assembly exposed to ultraviolet light.
The Annealing of Neutron Irradiation-Induced Defects in Silicon Carbide
Authors: Faulkner D. , Styles R.C. 
Published: June 2020

Radiation-induced changes in the macroscopic dimensions, lattice parameters, strength and thermal diffusivity of various types of silicon carbide suggest that different polytypes of this material may behave differently when subjected to a nuclear radiation field. This paper reports the existence of visible defects in post-irradiation annealed material.RFL (Springfields) self-bonded silicon carbide was irradiated in the WR-1 organic-cooled reactor. The specimens were exposed to a fast neutron fluence of 2.2×1020nvt (E>0.18 MeV) at a temperature of 700°C. Specimens suitable for examination in the electron microscope (3m.m × 1 m.m thick discs) were subsequently annealed for 4 hrs. at temperatures up to 2000°C. The material was ground down from both sides to approximately 0.25 m.m thick and ion thinned for examination in a Hitachi HU-200E electron microscope equipped with a 40° high resolution tilting stage.
Thin Substrate Structure and Electron Scattering after EM Beam Exposure
Authors: Hill Bruce C. , Haydon Glen B. 
Published: June 2020

Electron diffraction studies of organic substrates after electron beam exposure suggest that all have a common structure. As estimated by electron scattering, substrates produced from Parlodion appear to be thinner than those described by Williams et al. as being 7 AU thick.The changes in organic materials produced by electron irradiation have been investigated by a number of researchers. Bahr et al. showed that, in general, irradiation will cause mass loss and that a considerably larger proportion of carbon than of other elements is retained in the final product. For example, an exposure of 3 × 10−2 coulombs/cm2 at 75 kV caused a 54% mass loss and 25% carbon loss in a Formvar film. Earlier investigations showed a 75% mass loss in Parlodion (nitrocellulose) films at the same dose of 70 keV electrons. We have investigated the structural changes in common substrate materials using electron diffraction studies.
Determination of the Best Emulsion for the Microscopy of Crystals
Authors: Grano David A. , Downing Kenneth H. 
Published: June 2020

The retrieval of high-resolution information from images of biological crystals depends, in part, on the use of the correct photographic emulsion. We have been investigating the information transfer properties of twelve emulsions with a view toward 1) characterizing the emulsions by a few, measurable quantities, and 2) identifying the “best” emulsion of those we have studied for use in any given experimental situation. Because our interests lie in the examination of crystalline specimens, we've chosen to evaluate an emulsion's signal-to-noise ratio (SNR) as a function of spatial frequency and use this as our critereon for determining the best emulsion.The signal-to-noise ratio in frequency space depends on several factors. First, the signal depends on the speed of the emulsion and its modulation transfer function (MTF). By procedures outlined in, MTF's have been found for all the emulsions tested and can be fit by an analytic expression 1/(1+(S/S0)2). Figure 1 shows the experimental data and fitted curve for an emulsion with a better than average MTF. A single parameter, the spatial frequency at which the transfer falls to 50% (S0), characterizes this curve.
Quantitative Analysis of Electron Diffraction Pattern and Image of Crotoxin Complex Thin Crystal
Authors: Jeng T.W. , Chiu W. 
Published: June 2020

Crotoxin complex is the toxic principle in the venom of the South American rattlesnake, Crotalus durissus terrificus. This protein has two non-identical subunits and expresses its neurotoxicity via synergistic interaction. Unlike most of the neurotoxins isolated from snake venoms, this protein can have binding affinity to both post- and pre-synaptic membrane. We have reported earlier preliminary results of forming a thin crystal from this complex and of an electron diffraction pattern recorded to atomic resolution. The present paper is to discuss the space group symmetry of this protein crystal from the quantitative analysis of the electron diffraction intensities as well as of the low dose images.The crotoxin complex crystal was embedded in 1% glucose. The electron diffraction pattern and image were recorded on Kokak Industrex AA x-ray film with 0.1 e/Å2 and 2.5 e/Å2, respectively, at room temperature. These data were scanned with a Perkin-Elmer microdensitometer Model 1010. Figure 1 shows the original and the computer processed electron diffraction pattern.
Deformation Substructure in Cemented WC-Co Materials
Authors: Kenik E. A. , Krawitz A. D. , Drake E. F. 
Published: June 2020

The cemented refractory carbides represent one of the basic classes of materials used in machine cutting and rock drilling tools. These multiphase materials (a refractory carbide compact with a metallic binder phase) provide a good combination of hardness, toughness, and abrasion resistance which leads to long tool life. The present study investigates the microstructure of several cobalt-based cemented WC materials in response to different types of mechanical loading.The materials were hot isostatically pressed sintered compacts of WC and blends of cobalt and nickel metal powders (∼17 wt %). Three blends of metal powders were used: Co-1, Co-2, and Co-3 (in increasing nickel content). During the high-temperature sintering process, the metallic binder was molten, aiding the sintering reaction and also dissolving some WC into solution. Specimens were examined in the ORNL Hitachi HU-1000 high voltage electron microscope in the undeformed state and following different conditions of mechanical treatment: low (2.1 GPa) and high (3.4 GPa) stress compressive monotonic loading, and low (1.0 GPa) and high (2.1 GPa) stress compressive cyclic loading. The high penetration power of the HVEM allowed the examination of the microstructure of the dense WC grains and thicker binder regions where the dislocation structure would be representative of that in the bulk.
Formation of <100>/{100} Dislocation Loops in Electron-Irradiated Dilute Ni-Be Alloys
Authors: Mukai T. , Mitchell T. E. 
Published: June 2020

Radiation induced segregation (RIS) in alloys is becoming a common phenomenon during high temperature irradiations. Precipitate formation in solid solution alloys under irradiation (radiation induced precipitation) is a manifestation of RIS. In the present study we report the formation of <100>/{100} dislocation loops, together with the precipitation of G.P. zones on {100}, in under-saturated Ni-Be alloys during electron irradiation.Ni-1 at.% Be and Ni-0.3 at.% Be supplied by ANL were solution-annealed and quenched into water. Electron microscope specimens were irradiated with 650keV electrons at a flux of 1-5x1019e/cm2.s using a Hitachi HU-650B high voltage electron microscope. A specimen of Ni-1 at.% Be was irradiated at 470°C for 15 min. The [001] zone-axis diffraction pattern taken after the irradiation is shown in Fig. 1(a), where evolution of streaks along <100> is evident. The streaks come from G.P. zones on {100} planes.
Measurement of Sub-Micron Sized Grains in a Powder Metallurgy Alloy
Authors: Anderson D. M. , Coyne E. J. 
Published: June 2020

New concepts in airframe materials, including powder metallurgy (P/M) alloys and metal matrix composites, have been offered to aircraft manufacturers. These new materials have been suggested as alternatives to conventional ingot metallurgy products now used in airframes. Aircraft manufacturers must evaluate these materials to determine their suitability for airframe use. The stability of the small uniform grain size of prospective P/M alloys was a major concern since some of the proposed fabrication processes involved elevated temperatures. These processes typically have caused grain growth and loss of material properties in ingot materials.A mechanically alloyed, non-heat-treatable, P/M aluminum alloy, IN-9051 is produced by the Novamet Division, MPD Technology Corporation, an Inco Company. Previous research had indicated that elevated temperatures might adversely affect this material's properties. The effect of 16 combinations of elevated temperatures (600-900° F) and times at temperature on the grain size of each of three different extrusions was measured. A similar, but abbreviated, program on sheet material rolled from these extrusions was also conducted.
The Microstructure of Nickel Oxide Scales
Authors: Tinker M. T. , Hobbs L. W. 
Published: June 2020

There is considerable technological interest in oxidation of nickel because of the importance of nickel-base superalloys in high-temperature oxidizing environments. NiO scales on nickel grow classically, by outward diffusion of nickel through the scale, and are among the most studied of oxidation systems. We report here the first extensive characterization by transmission electron microscopy of nickel oxide scales formed on bulk nickel substrates and sectioned both parallel and transversely to the Ni/NiO interface.Electrochemically-polished nickel sheet of 99.995% purity was oxidized at 1273 K in 0.1 MPa oxygen partial pressure for times between 5 s and 25 h. Parallel sections were produced using a combination of electropolishing of the nickel substrate and ion-beam thinning of the scale to any desired depth in the scale. Transverse sections were prepared by encasing stacked strips of oxidized nickel sheet in epoxy resin, sectioning transversely and ion-beam thinning until thin area spanning one or more interfaces was obtained.
Lattice Imaging of Heteroepitaxial Silicon on Sapphire
Authors: Ponce Fernando A. 
Published: June 2020

The silicon-on-sapphire technology has produced electronic devices with high switching speeds and low power consumption. These features are mainly due to the insulating nature of the substrate and the consequent reduction in parasitic capacitances. TEM observations of the crystalline structure of the silicon layer reveal the presence of large densities of twins and stacking faults, which are thought to have an adverse effect on the overall electrical characteristics of the devices and it is, therefore, desirable to understand their nature and origin.In this work the lattice structure of the silicon-sapphire junction has been imaged by high resolution TEM. The silicon layer was deposited at 960°C by chemical vapor deposition of silane in H2, at a rate of 1.4 μm/min on a (1102) sapphire substrate surface. The silicon was grown with its [001] direction perpendicular to the substrate plane to a thickness of 0.65 μm. Specimens were prepared in cross section with argon-ion bombardment as the final thinning step. TEM observations were performed with a Philips EM400 microscope equipped with a high resolution stage (spherical aberration coefficient of 1.1 mm) and a LaB6 filament, at an operating voltage of 120 kV.
Analysis of Grain Boundary Precipitation in 7475 Al Alloys Using High Resolution and Analytical Electron Microscopy
Authors: Koo J. Y. , Park B. K. 
Published: June 2020

High resolution electron microscopy has considerably enhanced our understanding of phase transformation behaviors by providing details which supersede the resolution capabilities of other experimental techniques. This paper presents the analysis of grain boundary precipitation in 7475 alloy utilizing the lattice fringe imaging technique in conjunction with microdiffraction and X-ray microanalysis.The commercial 7475 alloy was solution heat treated at 900°F for 1-1/2 hr. and subsequently quenched to room temperature. The specimens were then given double aging treatments, 6 hrs. at 150°C plus 2 hrs. at 80°C. Thin foils were examined using a Philips 400 TEM equipped with FEG, twin lens, and energy dispersive X-ray unit. Figure 1 is the lattice fringe image showing a grain boundary precipitate (∼300Å dia.) growing into two neighboring PFZ across the boundary. Also shown in the micrograph is another precipitate (arrowed) nucleated at the junction between the grain boundary and the bigger particle. Energy dispersive X-ray spectra from the particles (dotted), partially shown in Figures 2 and 3 in comparison with those of matrix (bars), indicate that the major elements present are A1 and Mg (not shown), and Cr in the bigger particle, and A1 and Mg (not shown), Zn and Cu in the small precipitate.
Analytical Treatment of the Breakdown of Friedels Law. Application to Crystal Polarity Determination in Semiconductors with Sphalerite Structure
Authors: J. Taftø  
Published: June 2020

In a recent paper a simple method for determination of the direction of the polarity of noncentrosymmetric crystals was presented. The method was based on qualitative considerations. To test the validity of this method a three beam case where Friedels law does not apply is solved analytically. Based on the Bloch wave treatment (see e.g. ) we consider the situation shown in fig. la with Ug = Uh-g = U-h = V exp(iω) and both reflections at the Bragg position. The group of the dispersion matrix is C3 (or 3) and according to group character tables e.g. the coefficients of the Bloch waves are:By inserting these eigenvectors into the dispersion matrix we get the eigen-values:
Ion Beam Induced Interfacial Reactions in Molybdenum Thin Films on Silicon
Authors: Chen L. J. , Hung L. S. , Mayer J. W. 
Published: June 2020

When an energetic ion penetrates through an interface between a thin film (of species A) and a substrate (of species B), ion induced atomic mixing may result in an intermixed region (which contains A and B) near the interface. Most ion beam mixing experiments have been directed toward metal-silicon systems, silicide phases are generally obtained, and they are the same as those formed by thermal treatment.Recent emergence of silicide compound as contact material in silicon microelectronic devices is mainly due to the superiority of the silicide-silicon interface in terms of uniformity and thermal stability. It is of great interest to understand the kinetics of the interfacial reactions to provide insights into the nature of ion beam-solid interactions as well as to explore its practical applications in device technology.About 500 Å thick molybdenum was chemical vapor deposited in hydrogen ambient on (001) n-type silicon wafer with substrate temperature maintained at 650-700°C. Samples were supplied by D. M. Brown of General Electric Research & Development Laboratory, Schenectady, NY.
TEM In-Situ Epitaxy on Recrystallized Sapphire Substrates
Authors: Anton R. , Poppa H. , Heinemann K. 
Published: June 2020

The suitability of freshly recrystallized clean and well ordered alumina films for meaningful and reproducible in-situ studies of the nucleation, growth, and epitaxy of vapor-deposited materials was investigated, using Au, Ag, Fe, Pd, Mo, and W as deposit materials.A typical example of the dependence of the number density of nuclei on the substrate surface conditions is shown in Fig. 1. The highest density was found, as expected, in the polycrystalline substrate area (lower right); a lower particle number density, along with decoration of surface relief structures, was noted in the sapphire grain (upper right) near the boundary with the polycrystalline film; and the density is lowest on a (0001)-oriented α-Al2O3, grain which is also close to the center of the recrystallized area. This substrate region probably was hottest during the in-situ recrystallization process and is, therefore, low in defects and free of contaminants; gold deposited at 750°C was found to be nearly perfectly epitaxial, exhibiting good crystal lographic habits.
Efficient Algorithms for Computer Diffraction Pattern Analysis
Authors: Warren J. B. 
Published: June 2020

The increasing availability of position-sensitive radiation detectors has facilitated the automated analysis of electron diffraction patterns with computers. One problem that lends itself to solution by these methods is the computation of the electron beam-sample orientation from Kikuchi patterns. A precise orientation is required for a wide variety of problems including the determination of grain boundary misorientations, precipitate-matrix relationships and the computer simulation of crystal defect images. In all of these investigations the beam-sample relationship is required for several sample orientations and computational labor can be excessive unless some form of automated analysis is employed.If a position-sensitive detector composed of two arrays of elements is placed at the electron microscope phosphor screen position, the orientation can be determined directly from the diffraction pattern. As shown in Fig. 2, a rectangular detector array would detect many Kikuchi lines and the algorithm used to interpret data must be able to determine which Kikuchi line pairs are suitable for use in computation, choose the proper (hkl) lattice plane associated with the Kikuchi line pair, and finally index the chosen line pairs in a consistent manner.
A Color Coded STEM/SEM Image Storage System
Authors: Kokubo Y. , Hardy W. H. , Dance J. , Jones K. 
Published: June 2020

A color coded digital image processing is accomplished by using JEM100CX TEM SCAN and ORTEC’s LSI-11 computer based multi-channel analyzer (EEDS-II-System III) for image analysis and display. Color coding of the recorded image enables enhanced visualization of the image using mathematical techniques such as compression, gray scale expansion, gamma-processing, filtering, etc., without subjecting the sample to further electron beam irradiation once images have been stored in the memory.The powerful combination between a scanning electron microscope and computer is starting to be widely used 1) - 4) for the purpose of image processing and particle analysis. Especially, in scanning electron microscopy it is possible to get all information resulting from the interactions between the electron beam and specimen materials, by using different detectors for signals such as secondary electron, backscattered electrons, elastic scattered electrons, inelastic scattered electrons, un-scattered electrons, X-rays, etc., each of which contains specific information arising from their physical origin, study of a wide range of effects becomes possible.
Minimal Exposure, Rotary Hollow-Cone Illumination and Focus Wobble Added to The Deflection System of an HVEM
Authors: Pawley James B. 
Published: June 2020

Radiation damage places the fundamental limitation on the retrieval of structural information from co-valently bonded material by electron microscopy. Our interest here is simply to describe a system developed for the HVEM which will reduce to a practical minimum the amount of radiation to which the sample must be exposed in order to make a micrograph. Several methods have been described to accomplish this end in the 100 kV microscope. They usually involve pre-focusing on one area of the sample and then misaligning the column mechanically or by electromagnetic deflection in order to image a nearby part of the sample which remains unirradiated until just before the exposure of the micrograph. The only HVEM minimal exposure system seems to be the shutter fitted above the sample on the Cambridge 600 kV HREM.As the angular deviation caused by off axis displacement of the imaged area is inversely proportional to objective lens focal length, the degradation of imaging quality caused by such a displacement will be relatively less in the HVEM because of its longer focal length (EM-7 with side entry stage f=8.5mm).
Thermomechanical Treatment of a 4340 Ni-Cr-Mo Alloy Steel
Authors: Jahn M.T. , Yang J.C. , Wan C.M. 
Published: June 2020

4340 Ni-Cr-Mo alloy steel is widely used due to its good combination of strength and toughness. The mechanical property of 4340 steel can be improved by various thermal treatments. The influence of thermomechanical treatment (TMT) has been studied in a low carbon Ni-Cr-Mo steel having chemical composition closed to 4340 steel. TMT of 4340 steel is rarely examined up to now. In this study we obtain good improvement on the mechanical property of 4340 steel by TMT. The mechanism is explained in terms of TEM microstructures4340 (0.39C-1.81Ni-0.93Cr-0.26Mo) steel was austenitized at 950°C for 30 minutes. The TMTed specimen (T) was obtained by forging the specimen continuously as the temperature of the specimen was decreasing from 950°C to 600°C followed by oil quenching to room temperature. The thickness reduction ratio by forging is 40%. The conventional specimen (C) was obtained by quenching the specimen directly into room temperature oil after austenitized at 950°C for 30 minutes. All quenched specimens (T and C) were then tempered at 450, 500, 550, 600 or 650°C for four hours respectively.
Magnetic Domain Observation of an Amorphous Fe-Si-B Ribbon by Means of a High Voltage Scanning Electron Microscope
Authors: Tsuno K. , Harada Y. , Sato T. 
Published: June 2020

Magnetic domains of ferromagnetic amorphous ribbon have been observed using Bitter powder method. However, the domains of amorphous ribbon are very complicated and the surface of ribbon is not flat, so that clear domain image has not been obtained. It has been desired to observe more clear image in order to analyze the domain structure of this zero magnetocrystalline anisotropy material. So, we tried to observe magnetic domains by means of a back-scattered electron mode of high voltage scanning electron microscope (HVSEM).HVSEM method has several advantages compared with the ordinary methods for observing domains: (1) high contrast (0.9, 1.5 and 5% at 50, 100 and 200 kV) (2) high penetration depth of electrons (0.2, 1.5 and 8 μm at 50, 100 and 200 kV). However, image resolution of previous HVSEM was quite low (maximum magnification was less than 100x), because the objective lens cannot be excited for avoiding the application of magnetic field on the specimen.
Phase Contrast Imaging of Styrene/Isoprene Block Copolymers
Authors: Handlin Dale L. 
Published: June 2020

SAXS shows that in polystyrene (PS)/polyisoprene (PI) block copolymers with lamellar morphologies there is a sufficient electron density difference for x-ray scattering [1]. It has been accepted, however, that this difference is insufficient for TEM imaging by amplitude contrast. Therefore, contrast has been produced by staining the PI phase with OsO4 [2]. Staining changes the mechanical and chemical structure of the PI phase perhaps altering the phase separation and the domain interfaces (figure 1).Mean inner potential calculations, however, show potentials of 8.29V for PS and 7.57V for PI. This indicates that for a simple specimen geometry (e.g. lamellar) with sharp phase interfaces oriented parallel to the incident beam, a film 500Å thick will provide a phase change (Δψ) of 0.3 radians at 100 KV. This phase change is sufficient for imaging under defocus conditions and contains information about the interface region between the domains. The phase change may be increased by using lower voltage (50% increase at 40 KV).