Showing papers on "Microstructure published in 1978"
TL;DR: In this paper, Niobium-Nb wire composites with 0.105, 0.148, and 0.182 volume fraction of Nb filaments were produced in situ and their mechanical properties measured as a function of filament size and interfilament spacing.
Abstract: Cu‐Nb wire composites with 0.105, 0.148, and 0.182 volume fraction of Nb filaments were produced in situ and their mechanical properties measured as a function of filament size and interfilament spacing. The yield stress and the ultimate tensile strength increased with both niobium volume fraction and overall composite reduction. At room temperature, the ultimate tensile strength of the Cu–18.2 vol% Nb composite reduced by 99.999% in cross‐sectional area (100–200 A filament thickness) reached the value of 2230 MN/m2 (323 ksi) and further increased to 2850 MN/m2 (413 ksi) when measured at 77 °K. These values are higher by a factor of 4 than the values predicted by the rule of mixtures based on the highest reported strength of both niobium and copper. The composite strength is as high as that of the best copper whiskers and is shown to closely approach the theoretical strength of the material. The anomalous increase in strength despite the low volume fraction of reinforcing filaments suggests that the filam...
342 citations
TL;DR: In this paper, an attempt was made to relate the hardness of cemented tungsten carbide to its microstructure, and the concept of plastic limit analysis was used to evaluate the effect of the continous carbide phase on the hardness in WC-Co alloys.
328 citations
TL;DR: The feasibility of fabricating fiber-reinforced aluminum alloys by addition of discontinuous fibers to vigorously agitated, partially solid metal slurries was investigated in the first phase of the program as mentioned in this paper.
Abstract: The feasibility of fabricating fiber-reinforced aluminum alloys by addition of discontinuous fibers to vigorously agitated, partially solid metal slurries was investigated. In the first phase of the program, reported herein, emphasis was placed on the study of interface interactions between polycrystalline A12O3 fibers and Al-2 to 8 pct Mg, Al-4.5 pct Cu and Al-4.5 pct Cu-1 to 2 pct Mg alloys. In general, it was observed that the incorporation of fibers could be readily achieved by this technique, and that fibers appeared wetted after a few minutes of contact with the melt. The composites produced exhibited an intimate, void free bond between the constituents. In addition, a region of significantly altered microstructure resulted from accumulation of oxide and/or aluminate particles which either formed within the melt and were attached to the moving fibers, or used the fiber surface as a substrate to grow on. Microscopic examination of this interaction zone and thermodynamic considerations indicate that it consists of fine α-Al2O3, aluminates, oxides of the alloying elements, and probably some intermetallic compounds. For example, it is shown that a stable MgAl2O4 spinel forms at the interface of A12O3 fibers and Al-Mg alloys. Examination of composite specimens fractured under tension indicated that the interfaces produced were strong enough to permit the transfer of loads at strengths in the order of 250 to 350 MPa.
232 citations
TL;DR: In this paper, a cyclic step-process spall model was used to predict the parabolic rate constant, Rp, and the oxide spall fraction, Rs, from gravimetric curves.
Abstract: The Rinetics of A12O3 growth and spalling were observed for Ni-42 at. pct Al oxidized in air at 1100°C up to 1500 h. While crystallographic voids formed at the oxide-metal interface due to the oxidation process, the oxidation resistance was good in 1 h cycle tests. Spalling to bare metal was the predominant mode of oxide loss. The A12O3 grain size at the metal interface varied with a time-exponent of 0.2. In isothermal tests the oxide thicRness was nearly parabolic with time, having a time-exponent of 0.40, while the volume per void varied directly with residence time underneath intact oxide. The total void volume accounted for ~1/2 the aluminum needed to form the AI2O3 scale. In 1 h cycle tests the oxide thicRness and volume per void reached a plateau at ~150 h due to the spalling process. The correlation between total void volume and oxide volume was eventually obliterated by extensive cycling. A cyclic step-process spall model was used to predict the parabolic rate constant, Rp, and the oxide spall fraction, Rs, from gravimetric curves. Predicted values of Rp agreed well with experimental values, while predicted Rs values were often less than measured values. According to this model the severity of a long time test can be rated according to the factor fMe√ Rs · Rp · Δt mg/cm2 ·cycle, where fMe is the ratio of metal-to-oxygen in the oxide and Δt is the cycle time. Measured values of Rs in isothermal tests varied linearly with exposure time or approximately with (oxide thicRness).2 Cyclic tests showed more scatter and less dependence of Rs on oxide thicRness, presumably due to the complex oxide topography and relaxed stress states.
173 citations
TL;DR: The morphology and chemical analysis of the complex phases present in cast nickel aluminium bronze, of nominal composition 10% aluminium, 5% nickel and 5% iron, have been investigated using optical and electron microscopy techniques and energy dispersive analysis as mentioned in this paper.
Abstract: The morphology and chemical analysis of the complex phases present in cast nickel aluminium bronze, of nominal composition 10% aluminium, 5% nickel and 5% iron, have been investigated using optical and electron microscopy techniques and energy dispersive analysis. It has been shown that α, β and four forms of κ can exist in the ascast microstructure of this alloy. Heat treatment can lead to the precipitation of a further κ phase which differs in morphology and chemical composition to those present in ascast structures.
160 citations
TL;DR: In this article, it is shown that a cell structure can present many suitable pathways for subsurface crack generation and the release of thin wear flakes without the benefit of asperity cold welding and shear.
151 citations
Patent•
18 Dec 1978
TL;DR: Nickel base superalloy single crystal articles formed from an alloy family and heat treated are described as is the process employed as discussed by the authors, and the articles are substantially free from cobalt and the grain boundary strengtheners such as carbon, boron and zirconium.
Abstract: Nickel base superalloy single crystal articles formed from an alloy family and heat treated are described as is the process employed. The articles are substantially free from cobalt and the grain boundary strengtheners such as carbon, boron, and zirconium. The heat treatment process homogenizes the microstructure, and refines the gamma prime morphology.
144 citations
TL;DR: A microscopic examination of vapor- or sputter-deposited amorphous rare-earth transition-metal thin films reveals that they possess anisotropic microstructure as mentioned in this paper, and the morphology of the structure is similar in all of the films.
Abstract: A microscopic examination of vapor‐ or sputter‐deposited amorphous rare‐earth–transition‐metal thin films reveals that they possess anisotropic microstructure. The morphology of the structure is similar in all of the films. It consists of small (50–250 A in diameter) rod‐shaped regions of high density that are surrounded by a network of less‐dense material (10–25 A thickness). The column axes are mutually parallel and are oriented at an angle β that is described by the relationship: tanβ= (1/2) tanα, where α is the angle of incidence of the vapor beam, measured with respect to the substrate normal. The columnar structure is formed during deposition by self‐shadowing of the incident atoms by the atoms in the growing film. The columnar structure persists when multiple or distributed vapor sources are used to deposit the film. The structure is stable upon heating to temperaures in excess of the crystallization temperature of the amorphous deposits. Vapor deposition at large α leads to the formation of rowli...
142 citations
TL;DR: Fracture mechanics has been applied to the investigation of the failure of structural adhesives in humid environments as discussed by the authors, and the properties determining adhesive behaviour comprise T g, solubility parameter, surface free energy, viscosity and the microstructure of the polymer.
130 citations
01 Jan 1978
TL;DR: In this paper, the authors present a state-of-the-art system for sintering polycrystalline porcelain powders using fine-particle science, technology and characterisation.
Abstract: Keynote Address.- Some Considerations in the State of the Art in Processing Crystalline Ceramics.- I: Fine Particle Science, Technology and Characterization.- Physical and Chemical Parameters Controlling the Homogeneity of Fine Grained Powders and Sintering Materials.- Ultrafine Powders of Oxide and Non-Oxide Ceramic Materials and Their Sinterability.- Handling and Green Forming of Fine Powders.- The Potential of Fine Particle Technology Applied to Ceramic Raw Materials.- Particle Size and Permeability in Slip Casting.- Chemical Processing for Ceramics (and Polymers).- Ceramics Sintered Directly from Sol-Gels.- Characterization of Ceramic Microprocessing.- Packing and Sintering Relations for Binary Powders.- Stress and Density Distributions in the Compaction of Powders.- Pore Morphography in Ceramic Processing.- II: Solid State Sintering and Grain Growth.- Fundamentals of the Sintering of Ceramics.- Current Paradigms in Powder Processing.- Some Effects of Aggregates and Agglomerates in the Fabrication of Fine Grained Ceramics.- The Sintering of Conductive Rutile: A Model System for Sintering Electronic Ceramics.- Sintering of Mullite.- Rate Controlled Sintering as a Processing Method.- A Multiple-Lognormal Model of a Normal Grain Growth.- III: Liquid Phase Sintering And Post-Firing Technology.- Rearrangement During Liquid Phase Sintering of Ceramics.- Reactivity of Alumina Substrates with High Lead Glasses.- Influence of the Processing Parameters on the Properties of Rapid Fired Porcelain.- Strengthening of Lime-Stabilized Zirconia by Post Sintering Heat Treatments.- Strain and Surface Energy Effects in Ceramic Processes.- Dynamic and Material Parameters in Brittle Fracture in Ceramics.- Processing Induced Sources of Mechanical Failure in Ceramics.- IV: Dielectric and Magnetic Ceramics.- Processing of High Density Piezoelectric Ceramic Compositions.- The Role of ZrO2 Powders in Microstructural Development of PZT Ceramics.- Novel Uses of Gravimetry in the Processing of Crystalline Ceramics.- Deformation Processing of Magnetic Hexaferrites for Hc Maximization Through Grain Growth Control.- Processing and Magnetic Properties of Low-Loss and High-Stability Mn-Zn Ferrites.- Relationship Between Processing Conditions, Oxygen Stoichiometry and Strength of MnZn Ferrites.- Sintering of High Density Ferrites.- V: Energy Related Ceramics I: Fast Ion Conductors MHD, Nuclear and Refractory Ceramics.- Processing and Characterization of Polycrystalline ?"-Alumina Ceramic Electrolytes.- Microstructural Control During Sintering of ?"-Alumina Compositions Through Ceramic Processing Modification.- Transient Eutectics in Sintering of Sodium Beta Alumina.- Microstructural Evolution During the Processing of Sodium ?-Alumina.- Fabrication and Performance of MHD Electrodes.- Fabrication and Property Control of LaCrO3 Based Oxides.- Strontium Containing Perovskites and Related Conductive Electronic Ceramics.- Hot Pressed Composite Ceramic MHD Electrode Development.- Processing Variables Affecting the Thermomechanical Degradation of Monolithic Refractory Concretes.- UO2-Gd2O3 Sintering Behavior.- Processing Requirements for Property Optimization of EU2O3-W Cermets for Fast Reactor Neutron Absorber Applications.- Ceramic Processing of Boron Nitride Insulators.- VI: Energy Related Ceramics II: Non-Oxide Ceramics.- Grain Boundary Engineering in Non-Oxide Ceramics.- The Fabrication of Dense Nitrogen Ceramics.- Ceramics in the Si-Al-O-N System Fabricated by Conventional Powder Processing and Sintering Techniques.- Polytypism in Magnesium Sialons.- Dense Silicon Nitride Ceramics: Fabrication and Interrelations with Properties.- High-Pressure Hot-Pressing of Silicon Nitride Powders.- The Structure of Grain Boundaries in Silicon Nitride Based Alloys.- Evolution of Microstructure in Polycrystalline Silicon Carbide.- Thermal Gradient Deposition of SiC Diffusion Tracers.- Contributors.
126 citations
TL;DR: In this article, microstructural analysis of a 10 mol% Y/sub 2/O/sub 3/ fluxed hot-pressed silicon nitride reveals that, in addition to the yttrium-silicon oxynitride phase located at the multiple Si/Sub 3/N/sub 4/ grain junctions, there is a thin boundary phase 10 to 80 A wide separating the silicon nitric oxide and the oxynitic grains, suggesting that densification occurred by a liquid-phase ''solution-reprecipitation'' process.
Abstract: Detailed microstructural analysis of a 10 mol% Y/sub 2/O/sub 3/ fluxed hot-pressed silicon nitride reveals that, in addition to the yttrium-silicon oxynitride phase located at the multiple Si/sub 3/N/sub 4/ grain junctions, there is a thin boundary phase 10 to 80 A wide separating the silicon nitride and the oxynitride grains. Also, x-ray microanalysis from regions as small as 200 A across demonstrates that the yttrium-silicon oxynitride, Y/sub 2/Si(Si/sub 2/O/sub 3/N/sub 4/), phase can accommodate appreciable quantities of Ti, W, Fe, Ni, Co, Ca, Mg, Al, and Zn in solid solution. This finding, together with observations of highly prismatic Si/sub 3/N/sub 4/ grains enveloped by Y/sub 2/Si(Si/sub 2/O/sub 3/N/sub 4/), suggests that densification occurred by a liquid-phase ''solution-reprecipitation'' process.
TL;DR: In this article, the microstructure of reaction-bonded (this articleEL) silicon carbide has been quantitatively characterized using transmission and scanning electron microscopy, optical microscopy and electron and X-ray diffraction techniques.
Abstract: Quantitative characterization of the microstructure of a number of samples of reactionbonded (REFEL) silicon carbide has been undertaken employing transmission and scanning electron microscopy, optical microscopy, and electron and X-ray diffraction techniques. Impurity-controlled secondary electron SEM image contrast has proved particularly useful in differentiating between the SiC present in the initial compact and that formed during the reaction-bonding process, and, in contrast to previous descriptions of the microstructure, it has been found that the newly-formed SiC is deposited from the supersaturated solution of carbon in molten silicon both epitaxially on the original SiC grains, maintaining the sameα-polytypic stacking sequences, and by nucleation of fine cubicβ-SiC elsewhere. The relative quantities of material occurring by these two mechanisms have been found to vary from sample to sample, although the epitaxial growth on the original grains always occurs to some extent and is responsible for the bulk cohesion of the material. Some conclusions have been drawn concerning the reaction model and the process parameters controlling the microstructure of this type of material.
01 Jan 1978
TL;DR: In this article, the relationship between the microstructure and magnetic properties of heat treated Fe-23 wt percent Cr -15 wt% Co-5 wt % V has been studied by transmission electron microscopy and Lorentz microscopy.
Abstract: The relationship between the microstructure and magnetic properties of heat treated Fe-23 wt percent Cr--15 wt percent Co--5 wt percent V has been studied by transmission electron microscopy and Lorentz microscopy. Three different heat treatments were adopted for the present investigations viz., (1) isothermal aging, (2) TMT (thermomagnetic treatment) + step-aging, (3) continuous cooling. It has been found that the magnetic properties of the alloy are very sensitive to the temperature of the thermomagnetic treatment. Step-aging gave the best magnetic properties, producing an elongated ferromagnetic phase, 300 A in diameter and 1200 A in length. Lorentz microscopy revealed domain walls and these lie within the Cr-rich phase and pinned by the Fe-rich phase in the isothermally aged alloy at 650/sup 0/C. Magnetic domains of optimally step-aged alloy, 0.5 ..mu..m in width, are elongated along the direction of the applied magnetic field. The results suggest that the magnetic anisotropy is introduced parallel to the direction of the applied magnetic field during TMT and step-aging treatments.
TL;DR: In this article, the abrasive wear resistance of several pure metals, and two steels heat treated to produce a range of different microstructures, was determined using a pin-abrasion machine in which a small pin of the test material is ground on an abrasive cloth under controlled conditions.
TL;DR: In this paper, the authors react thin Pt, Pd, and Ni films with singlecrystal Si using Q-switched Nd/Ni laser pulses of 100nsec duration in the power range 18-50 MW cm−2.
Abstract: We have reacted thin Pt, Pd, and Ni films with single‐crystal Si using Q‐switched Nd : YAG laser pulses of 100‐nsec duration in the power range 18–50 MW cm−2. The layers are laterally very uniform in thickness but are not single phase. Average composition of the reaction product layer can be changed over a wide range by varying film thickness and laser power. The microstructure of the reacted layers indicates that reaction occurs via surface melting, mixing, and rapid resolidification.
TL;DR: In this article, a scanning laser beam was used to melt and normalize the surface layer of sensitized 304 stainless steel and Strauss tests indicated a complete resistance to intergranular corrosion.
Abstract: A scanning laser beam was used to melt and normalize the surface layer of sensitized 304 stainless steel. Subsequent Strauss tests indicated a complete resistance to intergranular corrosion. Mechanical testing at strains less than 15% also showed laser surface melting to indefinitely extend specimen life in a stress corrosion environment. At strains greater than 15%, the laser‐scanned protective layer was breached by cracks. A maximum critical laser‐scanning velocity compatible with normalization of the surface layer is calculated. Similarly, a minimum critical laser‐scanning velocity required to avoid resensitization is determined. The stress distribution in a 304 stainless‐steel specimen with a laser‐melted and self‐quenched surface layer is estimated and shown to be compatible with the observed appearance of martensite in the melted surface layer.
TL;DR: In this paper, the authors measured the sodium ion resistivity of polycrystalline β-alumina as a function of temperature for fine-grained and coarsegrained specimens with a chemical composition of 8.80 Na20-0.75 Li2O-90.45 A12O3 (wt%).
Abstract: The sodium ion resistivity of lithia-stabilized polycrystalline β”-alumina was measured as a function of temperature for fine-grained and coarse-grained specimens with a chemical composition of 8.80 Na20-0.75 Li2O-90.45 A12O3 (wt%). A model is presented which explains the dependence of sodium ion resistivity on grain size. Using the model the activation energy was determined for the transport of sodium ions across a grain boundary in this form of sodium β”-alumina.
TL;DR: In this article, the authors have calculated the strain-rate and temperature field in which ductility would be enhanced by diffusion at elevated temperature diffusion can relax these stress-concentrations and enhance ductility.
TL;DR: In this paper, the microstructures of permanent magnet alloys after isothermal aging, thermomagnetic treatment, and step aging have been characterized by transmission electron microscopy and by measurement of the Curie temperature.
Abstract: The microstructures of an Fe-31wt%Cr-23wt%Co ductile permanent magnet alloy after isothermal aging, thermomagnetic treatment, and step aging have been characterized by transmission electron microscopy and by measurement of the Curie temperature. Isothermal aging itself produces the undesirable microstructure. Aging at 600°C develops the magnetic chromium-rich phase. Aging at 600°C produces a nonmagnetic chromium-rich phase dispersed within the iron-rich phase. The effect of thermomagnetic treatment on the microstructure of the alloy is discussed in comparison with that of Alnico alloys. Step aging produces the deskable microstructure, viz., the elongated ferromagnetic phase imbedded in the paramagnetic phase.
TL;DR: In this article, the structure of Ni-P electrodeposited thin films with 7, 12, 20 and 22 at. pct P was studied and it was shown that grain size decreases with increasing P content; the present findings agree with previous ones.
Abstract: Electron microscopy has been used to study the structure of Ni-P electrodeposited thin films with 7, 12, 20 and 22 at. pct P. For the crystalline as-deposited films with 7 and 12 at. pct P (low P films), the crystal structure is fcc and the grains are a supersaturated solid solution of P in Ni. Grain size decreases with increasing P content; the present findings agree with previous ones. For “amorphous” as-deposited films with 20 and 22 at. pet P (high P content films) the amorphous phase is not completely homogeneous and there are regions in which small microcrystals exist. Electron beam heating a low P con-tent film causes the crystalline array of supersaturated Ni grains to decompose to an equilibrium mixture of Ni and Ni3P; both types of grains are randomly oriented. Electron beam heating a high P content film causes the amorphous regions to undergo several complex transformations. The first reaction to occur is: Amorphous (Ni-P) -NixPy + Ni (random) where NixPy is a newly discovered phase with a variable composition. Further beam heating causes a second transformation to equilibrium phases: NixPy + Ni → Ni3P + Ni (random). The microstructure resulting from the above transformations depends on variations in composition of the as-deposited specimens, rates of heating and temperature gradients. The mode of phase transformation in microcrystalline regions and amorphous regions is distinctly different. Crystallization in amorphous regions occurs by a nucleation and growth of NixPy, and Ni; a crystallization front is seen to advance into the amorphous re-gion. Crystallization in microcrystalline regions occurs by nucleation and growth of the Ni3P phase and grain coarsening of the Ni phase. No distinct crystallization front is ob-served.
TL;DR: In this paper, the X-ray results suggest that the mixed oxide coatings prepared at 400° C are best described as a metastable solid solution of the two components and the resistivity-composition relationship however is more indicative of a finely interdispersed mixture of conducting and insulating particles.
Abstract: Mixed oxide coatings consisting of varying proportions of RuO2 and TiO2 have been prepared on titanium and silica substrates. Development of the microstructure was examined by X-ray diffraction and also monitored by resistivity measurements. The X-ray results suggest that the mixed oxide coatings prepared at 400° C are best described as a metastable solid solution of the two components. The resistivity-composition relationship however is more indicative of a finely interdispersed mixture of conducting and insulating particles. Coatings fired at higher temperatures (700–800° C) exhibit separate X-ray diffraction peaks corresponding to almost pure RuO2 and TiO2 phases with no evidence of significant solid solubility.
TL;DR: In this article, the existing and distributing states of crystal phases in the non-ohmic zinc oxide ceramics with five additives, 0.5Bi2O3, 1.0Sb 2 O3, 0.,5Co 2O3 and 0,5MnO2, were investigated by using various analytical techniques.
Abstract: The existing and distributing states of crystal phases in the nonohmic zinc oxide ceramics with five additives, 0.5Bi2O3, 1.0Sb2O3, 0.5Co2O3, 0.5MnO2 and 0.5Cr2O3 (mol.%) were investigated by using various analytical techniques. The ceramics consist of the ZnO and spinel phases and mixed phases of β-and δ-Bi2O3. The ZnO phase corresponds to the main constituent grains, which are single crystals 10 to 20 microns in size with a twinning structure and randomly orientated. The spinel phase corresponds to single crystal grains a few microns in size, which are discontinuously located along comparatively wide grain boundaries. The Bi2O3 phases correspond to continuously spreading intergranular layers, which separate the ZnO grains from each other. The width of the interanular layers in the narrow grain boundaries between two adjacent ZnO grains is less than 500 A.
TL;DR: In this paper, the effect of hydrogen penetration of grain boundaries in Al-Zn-Mg alloys was studied at high resolution in the JEM 100 C transmission electron microscope as a function of alloy composition and ageing treatment.
Abstract: Al-Zn-Mg alloys become embrittled during exposure to moist environments due to hydrogen penetration of grain boundaries. The result of this hydrogen penetration due to surface reaction with water vapour of both bulk specimens and electron-transparent “thin foils”, has been studied at high resolution in the JEM 100 C transmission electron microscope as a function of alloy composition and ageing treatment. In bulk specimens of alloys solution-heated, water-quenched, and aged in water-vapour-saturated air at 70° C, the hydrogen is in the form of a mobile atomic species which is transformed to bubbles of molecular hydrogen under the action of the electron beam. However, in electron-transparent specimens of aged alloys after exposure to water vapour the accumulated hydrogen is observed directly as bubbles. These bubbles take the form of hexagonal lenses bounded by {111} planes, and are associated with grain-boundary precipitates, particularly in over-aged microstructures, and with primary intermetallic particles in alloys containing sparingly soluble transition elements. The consequence of the observed hydrogen penetration of grain boundaries in promoting environmental debilitation of mechanical properties and stress-corrosion cracking of Al-Zn-Mg alloys is discussed.
TL;DR: An extreme value approach for attenuation analysis has been developed, based on numerical scattering cross sections and an extreme value characterization of the microstructure as mentioned in this paper, for a range of ceramic polycrystals.
Abstract: Ultrasonic attenuation has been measured for a range of ceramic polycrystals. An extreme‐value approach for attenuation analysis has been developed, based on numerical scattering cross sections and an extreme‐value characterization of the microstructure. A good correlation between predicted and measured attenuation has been obtained in each case. The implications of the analysis for ultrasonic failure prediction and microstructural characterization have been explored.
TL;DR: In this paper, the preparation of a bloceramic material is described, which resembles natural bone in its chemical composition and in its porous structure, and the relationship between preparation conditions and crystallographic structure, microstructure and strength is discussed.
TL;DR: In this paper, the electrical resistivity of InGe, PbGe and AlGe mixtures co-evaporated onto room temperature substrates was measured by transmission electron microscopy.
TL;DR: In this article, the microstructure of soybean protein aggregates was examined by the optical microscope and the scanning electron microscope, and the effects of heat and coagulating agents on the micro structure of the aggregates and on the physical and textural properties of the protein curd were investigated.
Abstract: The microstructure of soybean protein aggregates was examined by the optical microscope and the scanning electron microscope. The effects of heat and coagulating agents on the microstructure of the aggregates and on the physical and textural properties of the protein curd were investigated. Isoelectric point precipitation and calcium coagulation did not change the globular structure of the native soybean protein. However, heating induced the destruction of the native protein body. Heat denaturation of the protein was necessary in forming the network structure of the aggregates. When the protein aggregates were frozen, their structure became better defined and enlarged. The three dimensional network structure of the aggregate derived from heated soybean protein showed a low sedimentation rate, high curd yield, high water-holding capacity, low value of hardness and high springiness compared to the unheated precipitates of globular structure.
TL;DR: In this paper, a detailed microstructural study of three slates by high voltage transmission electron microscopy is reported, and the initiation of cleavage lamellae can be clearly observed in electron micrographs from one of the slates studied.
Abstract: A detailed microstructural study of three slates by high voltage transmission electron microscopy is reported. The slates are mineralogically similar, come from minor fold cores and exhibit differing degrees of cleavage intensity. All three slates have domains of orientated phyllosilicates (cleavage lamellae) which contain only a low percentage of quartz and carbonate. Between these lamellae are lenticular domains which contain deformed phyllosilicates and which are enriched in secondary minerals. The initiation of cleavage lamellae can be clearly observed in electron micrographs from one of the slates studied. It occurs along zones of intense deformation, viz. along kinks and microfolds, which form from initial crenulations that are difficult to detect in a petrological microscope.
TL;DR: Laser surface melting experiments have been carried out on the refractory-element-rich alloy M2 and the chromium-rich Alloy 440-C as mentioned in this paper, where the microstructure contains both δ-ferrite and austenite with residual amounts of carbides.
TL;DR: The case microstructure and fracture of a coarse-grained 8620 steel carburized to 1 pet surface carbon are quite sensitive to austenitizing conditions and scanning electron microscopy shows both microvoid coalescence around the carbide particles and an apparent fine cleavage in other areas.
Abstract: The case microstructure and fracture of a coarse-grained 8620 steel carburized to 1 pet surface carbon are quite sensitive to austenitizing conditions. Reheating martensitic speci-mens below theAcm produces in the case a refined austenitic grain size, a very fine mar-tensite, spherical carbide particles and a minimum of retained austenite and microcrack-ing. Overload fracture through the latter microstructure is transgranular and scanning electron microscopy shows both microvoid coalescence around thecarbide particles and an apparent fine cleavage in other areas. As-carburized specimens and specimens re-austenitized above theAcm developed a case microstructure characterized by a coarse austenitic grain structure in which plate martensite with microcracks developed on cool-ing within a large amount of retained austenite. The overload fracture through this mi-crostructure followed a predominately intergranular path and effectively by-passed the retained austenite and microcracked martensite. Auger electron analysis showed that C and P were present on the intergranular fracture surfaces at concentrations above bulk, an observation consistent with literature reports of P segregation during austenitizing.