Grain Morphology and Intergranular Structure of Si3N4 Based Ceramics Formed by Hip

1992 ◽  
Vol 287 ◽  
Author(s):  
H. BjÖrklund ◽  
L. K. L. Falk ◽  
J. WasÉn ◽  
J. E. Adlerborn ◽  
H. T. Larker
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Metal Oxides ◽  
Grain Growth ◽  
Analytical Electron Microscopy ◽  
Grain Morphology ◽  
Quantitative Microscopy ◽  
Analytical Electron ◽  
Sic Whiskers ◽  
Matrix Morphology

ABSTRACTThe microstructures of unreinforced and reinforced Si3N4 ceramics have been characterized by analytical electron microscopy in combination with quantitative microscopy. Special attention was paid to the effect which different additives, viz. metal oxides and SiC- and β-Si3N4-whiskers, have upon matrix morphology and intergranular microstructure. It was demonstrated that SiC-whiskers may suppress Si3N4 grain growth while an addition of β-Si3N4-whiskers results in a coarser Si3N4 microstructure. The different microstructures have been related to the mechanical properties of the ceramics.

Local Mechanical Properties of Cu-Co Alloys with Coherent Co Precipitates

2015 ◽  
Vol 662 ◽  
pp. 15-18
Author(s):  
Jiří Buršík ◽  
Vilma Buršíková ◽  
Milan Svoboda
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Solid Solution ◽  
Thermal Treatment ◽  
Analytical Electron Microscopy ◽  
Water Quenching ◽  
Large Area ◽  
Analytical Electron ◽  
Indentation Tests ◽  
Co Alloys

In this work the influence of the thermal treatment on the local mechanical properties of model diluted Cu-Co alloys with Co content of 4 at.% is investigated. The samples underwent annealing at 1273 K followed by water quenching. The further thermal treatment at 1073 K of the oversaturated solid solution generated a fine distribution of Co-rich precipitates. Parameters of microstructure were evaluated by means of analytical electron microscopy. The nanoscale mechanical properties of precipitates, areas adjacent to the precipitates and precipitate-free zones were studied using large area grid indentation tests. Moreover, the modulus mapping capability was applied to obtain quantitative maps of the storage and loss stiffness and modulus.

An analytical electron microscopy investigation of municipal solid waste incineration bottom ash

1998 ◽  
Vol 13 (1) ◽  
pp. 28-36 ◽  
Author(s):  
James E. Krzanowski ◽  
T. Taylor Eighmy ◽  
Bradley S. Crannell ◽  
J. Dykstra Eusden
Keyword(s):  
Electron Microscopy ◽  
Metal Oxides ◽  
Amorphous Material ◽  
Analytical Electron Microscopy ◽  
Bottom Ash ◽  
Waste Incineration ◽  
High Density ◽  
Leaching Behavior ◽  
Microscopy Investigation ◽  
Analytical Electron

Incinerator bottom ash samples have been characterized using analytical electron microscopy (AEM) techniques, including electron diffraction, energy dispersive spectroscopy, and electron energy loss spectroscopy. The samples were first separated by magnetic properties and density. Three resulting fractions were examined: the magnetic, high-density (MHD) fraction, the nonmagnetic/high-density (NMHD) fraction, and the nonmagnetic, low-density (NMLD) fraction. Examination of these samples revealed a variety of submicron microstructural features. For the MHD fraction, metal oxides, iron silicates, aluminum silicates, and calcium phosphate compounds were found in addition to amorphous material. The NMHD fraction contained elements similar to the MHD fraction but had more amorphous material; crystalline silicates were less common. Compounds such as MgO and chloroapatite were also found. The NMLD fraction contained SiO2 and numerous metal oxides. The results of some of these analyses were used to model leaching behavior of the ash. Based on the AEM results, three mineral phases were chosen as candidates for aqueous geochemical thermodynamic equilibrium modeling of pH-dependent leaching: chromite, chloroapatite, and zincite. In two of these three cases (chromite, chloroapatite), the selected mineral phase provided excellent agreement with the experimentally observed leaching behavior. AEM was shown to be a useful tool for elucidating mineralogy of complex environmental samples.

Microstructure Characterization of Tungsten Based Alloys for Fusion Application

2013 ◽  
Vol 58 (2) ◽  
pp. 473-476 ◽  
Author(s):  
G. Cempura ◽  
A. Kruk ◽  
C. Thomser ◽  
M. Wirtz ◽  
A. Czyrska-Filemonowicz
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Electron Tomography ◽  
Analytical Electron Microscopy ◽  
Large Scatter ◽  
Fine Grained ◽  
Analytical Electron ◽  
The Matrix ◽  
Strengthening Particles

The microstructure of two tungsten based alloys (W-1.1%TiC and W-1.7% TiC) was characterized using light microscopy, analytical electron microscopy and electron tomography. These alloys represent a class of W based dispersion strengthened alloys with TiC used as strengthening particles. Addition of TiC leads to improved creep resistance and tensile strength of the W based alloys. The results show that the W-1.7%TiC alloy exhibits large scatter in grain size, much higher porosity and contains also Ti-O particles. The W-1.1%TiC alloy has fine grained microstructure with uniformly distributed fine TiC particles within the matrix and low porosity. As a result of the different microstructure, the W-1.1%TiC alloy exhibits better mechanical properties, when compared to the W-1.7%TiC alloy.

Analytical Electron Microscopy of a Polymer Blend

1985 ◽  
Vol 43 ◽  
pp. 80-81
Author(s):  
T. Haddock ◽  
S.J. Krause ◽  
S. Kumar ◽  
W.W. Adams
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Polymer Blend ◽  
Analytical Electron Microscopy ◽  
High Strength ◽  
X Ray ◽  
Analytical Electron ◽  
Flexible Coil ◽  
Electron Energy Loss ◽  
Beam Damage

A polymer blend which is composed of poly-p-phenylene benzobisthiazole (PBT) and poly-2,5(6)benzimidazole (ABPBI) has been processed into both a phase-separated material and a “molecular composite”. In the molecular composite, the PBT and ABPBI components are dispersed at a scale finer than 3 nm. This results in high mechanical properties as the rod-like, high strength PBT reinforces the flexible-coil ABPBI matrix. In the phase- separated blend, micron-sized aggregates form within a more ductile matrix. This study qualitatively examines the structure and composition of the phase- separated 20% PBT / 80% ABPBI blend using the analytical electron microscopy (AEM) techniques of energy dispersive x-ray spectroscopy (EDS), electron energy loss spectroscopy (EELS), and microdiffraction. Beam damage of the components is also considered.

A comparison of the interphase development and mechanical properties of Nicalon and Tyranno SiC fiber-reinforced ZrTiO4 matrix composites

1994 ◽  
Vol 9 (10) ◽  
pp. 2670-2676 ◽  
Author(s):  
B.A. Bender ◽  
T.L. Jessen
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Analytical Electron Microscopy ◽  
Fiber Composites ◽  
Matrix Composites ◽  
Fiber Reinforced ◽  
Sic Fiber ◽  
Transmission Electron ◽  
Fiber Clustering ◽  
Analytical Electron

The differences in interphase development and mechanical properties between Nicalon and Tyranno fiber-reinforced ZrTiO4 matrix composites were assessed. The composites were reinforced with either uncoated or BN-coated fibers. The microstructure and interphase development were analyzed using scanning electron microscopy, transmission electron microscopy, and analytical electron microscopy. Mechanical behavior was characterized by strength and toughness measurements. Tyranno composites developed thinner interphases due to the differences in the structure and chemistry of the starting fiber resulting from the addition of Ti to the starting polymer precursor. BN-coated fiber composites developed a thicker carbon interphase layer due to incorporation of O into the as-received BN coating. Tyranno composites were weakened by fiber clustering and were not as tough as Nicalon composites due to a lack of thermal debonding.

Electron Beam Damage of Biomolecules Assessed by Energy Loss Spectroscopy

1978 ◽  
Vol 36 (3) ◽  
pp. 61-69
Author(s):  
M. Isaacson ◽  
M.L. Collins ◽  
M. Listvan
Keyword(s):  
Electron Microscopy ◽  
Radiation Damage ◽  
Structural Integrity ◽  
Analytical Electron Microscopy ◽  
High Dose ◽  
Dose Rates ◽  
Special Cases ◽  
Analytical Electron ◽  
Atom Migration ◽  
Beam Damage

Over the past five years it has become evident that radiation damage provides the fundamental limit to the study of blomolecular structure by electron microscopy. In some special cases structural determinations at very low doses can be achieved through superposition techniques to study periodic (Unwin & Henderson, 1975) and nonperiodic (Saxton & Frank, 1977) specimens. In addition, protection methods such as glucose embedding (Unwin & Henderson, 1975) and maintenance of specimen hydration at low temperatures (Taylor & Glaeser, 1976) have also shown promise. Despite these successes, the basic nature of radiation damage in the electron microscope is far from clear. In general we cannot predict exactly how different structures will behave during electron Irradiation at high dose rates. Moreover, with the rapid rise of analytical electron microscopy over the last few years, nvicroscopists are becoming concerned with questions of compositional as well as structural integrity. It is important to measure changes in elemental composition arising from atom migration in or loss from the specimen as a result of electron bombardment.

Analytical Electron Microscopy (AEM) of Meningeal Cells Exposed to Particulate Cobalt During Studies of Experimental Epilepsy

1982 ◽  
Vol 40 ◽  
pp. 186-187
Author(s):  
R.G. Frederickson ◽  
R.G. Ulrich ◽  
J.L. Culberson
Keyword(s):  
Electron Microscopy ◽  
Analytical Electron Microscopy ◽  
Experimental Epilepsy ◽  
Metallic Cobalt ◽  
Experimental Animals ◽  
X Ray ◽  
Brain Surface ◽  
Meningeal Cells ◽  
Analytical Electron ◽  
The Brain

Metallic cobalt acts as an epileptogenic agent when placed on the brain surface of some experimental animals. The mechanism by which this substance produces abnormal neuronal discharge is unknown. One potentially useful approach to this problem is to study the cellular and extracellular distribution of elemental cobalt in the meninges and adjacent cerebral cortex. Since it is possible to demonstrate the morphological localization and distribution of heavy metals, such as cobalt, by correlative x-ray analysis and electron microscopy (i.e., by AEM), we are using AEM to locate and identify elemental cobalt in phagocytic meningeal cells of young 80-day postnatal opossums following a subdural injection of cobalt particles.

Analytical Electron Microscopy Characterization of Electric Arc Furnace Dust

1981 ◽  
Vol 39 ◽  
pp. 134-135
Author(s):  
J. R. Porter ◽  
J. I. Goldstein ◽  
D. B. Williams
Keyword(s):  
Electron Microscopy ◽  
Analytical Electron Microscopy ◽  
Electric Arc Furnace ◽  
Electric Arc ◽  
Dust Particles ◽  
Particle Analysis ◽  
Arc Furnace ◽  
Analytical Electron ◽  
Residual Elements ◽  
Industry Practice

Alloy scrap metal is increasingly being used in electric arc furnace (EAF) steelmaking and the alloying elements are also found in the resulting dust. A comprehensive characterization program of EAF dust has been undertaken in collaboration with the steel industry and AISI. Samples have been collected from the furnaces of 28 steel companies representing the broad spectrum of industry practice. The program aims to develop an understanding of the mechanisms of formation so that procedures to recover residual elements or recycle the dust can be established. The multi-phase, multi-component dust particles are amenable to individual particle analysis using modern analytical electron microscopy (AEM) methods.Particles are ultrasonically dispersed and subsequently supported on carbon coated formvar films on berylium grids for microscopy. The specimens require careful treatment to prevent agglomeration during preparation which occurs as a result of the combined effects of the fine particle size and particle magnetism. A number of approaches to inhibit agglomeration are currently being evaluated including dispersal in easily sublimable organic solids and size fractioning by centrifugation.

Application of analytical electron microscopy to the study of partitioning of silicon in a 2 wt% Si eutectoid steel

1978 ◽  
Vol 36 (1) ◽  
pp. 616-617
Author(s):  
N. Ridley ◽  
S.A. Al-Salman ◽  
G.W. Lorimer
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Analytical Electron Microscopy ◽  
Eutectoid Steel ◽  
Minimum Diameter ◽  
Thin Foils ◽  
Analytical Electron ◽  
Analytical Electron Microscope ◽  
Transformation Front

The application of the technique of analytical electron microscopy to the study of partitioning of Mn (1) and Cr (2) during the austenite-pearlite transformation in eutectoid steels has been described in previous papers. In both of these investigations, ‘in-situ’ analyses of individual cementite and ferrite plates in thin foils showed that the alloying elements partitioned preferentially to cementite at the transformation front at higher reaction temperatures. At lower temperatures partitioning did not occur and it was possible to identify a ‘no-partition’ temperature for each of the steels examined.In the present work partitioning during the pearlite transformation has been studied in a eutectoid steel containing 1.95 wt% Si. Measurements of pearlite interlamellar spacings showed, however, that except at the highest reaction temperatures the spacing would be too small to make the in-situ analysis of individual cementite plates possible, without interference from adjacent ferrite lamellae. The minimum diameter of the analysis probe on the instrument used, an EMMA-4 analytical electron microscope, was approximately 100 nm.

Analytical electron microscopy of grain boundaries in Al-Cu metallizations

1992 ◽  
Vol 50 (2) ◽  
pp. 1684-1685
Author(s):  
J. R. Michael ◽  
A. D. Romig ◽  
D. R. Frear
Keyword(s):  
Electron Microscopy ◽  
Integrated Circuits ◽  
Failure Mode ◽  
Current Density ◽  
Thermal History ◽  
Analytical Electron Microscopy ◽  
Cu Metallization ◽  
Analytical Electron ◽  
Interconnect Lines

Al with additions of Cu is commonly used as the conductor metallizations for integrated circuits, the Cu being added since it improves resistance to electromigration failure. As linewidths decrease to submicrometer dimensions, the current density carried by the interconnect increases dramatically and the probability of electromigration failure increases. To increase the robustness of the interconnect lines to this failure mode, an understanding of the mechanism by which Cu improves resistance to electromigration is needed. A number of theories have been proposed to account for role of Cu on electromigration behavior and many of the theories are dependent of the elemental Cu distribution in the interconnect line. However, there is an incomplete understanding of the distribution of Cu within the Al interconnect as a function of thermal history. In order to understand the role of Cu in reducing electromigration failures better, it is important to characterize the Cu distribution within the microstructure of the Al-Cu metallization.

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