Analytical Electron Microscopy of Phase Growth. In The Fe-Ni-P System

1982 ◽  
Vol 40 ◽  
pp. 718-719
Author(s):  
C. Narayana
Keyword(s):  
Binary Systems ◽  
Analytical Electron Microscopy ◽  
Ternary Systems ◽  
P System ◽  
Phase Growth ◽  
Diffusional Growth ◽  
Equilibrium Partitioning ◽  
Analytical Electron ◽  
Two Phases ◽  
Solute Species

Solid state precipitation by classical nucleation and diffusional growth, in binary systems, requires equilibrium partitioning of the solute between the two phases. In ternary systems where one solute diffuses much faster than the other, partitioning of the slower diffusing solute species, between the two phases, is not necessary. In Fe-X-Y alloys, where X is a slow diffusing element and Y a fast diffusing element, the growth of ferrite often occurs without any significant partitioning of element X.

Correlations of Equilibrium Interfacial Tension Based on Mutual Solubility/Density: Extension to n-Alkane–Water and n-Alkane–CO2 Binary/Ternary Systems and Comparisons With the Parachor Model

2019 ◽  
Vol 141 (12) ◽  
Author(s):  
Zehua Chen ◽  
Daoyong Yang
Keyword(s):  
Interfacial Tension ◽  
Binary Systems ◽  
Ternary Systems ◽  
Liquid System ◽  
Mutual Solubility ◽  
Density Difference ◽  
Petroleum Engineering ◽  
Liquid Density ◽  
Relative Deviation ◽  
Two Phases

In this study, new and pragmatic interfacial tension (IFT) correlations for n-alkane–water and n-alkane–CO2 systems are developed based on the mutual solubility of the corresponding binary systems and/or density in a pressure range of 0.1–140.0 MPa and temperature range of 283.2–473.2 K. In addition to being more accurate (i.e., the absolute average relative deviation (AARD) is 1.96% for alkane–water systems, while the AARDs for alkane–CO2 systems are 8.52% and 25.40% in the IFT range of >5.0 mN/m and 0.1–5.0 mN/m, respectively) than either the existing correlations or the parachor model (the AARDs for alkane–CO2 systems are 12.78% and 35.15% in the IFT range of >5.0 mN/m and 0.1–5.0 mN/m, respectively), such correlations can be applied to the corresponding ternary systems for an accurate IFT prediction without any mixing rule. Both a higher mutual solubility and a lower density difference between two phases involved can lead to a lower IFT, while pressure and temperature exert effects on IFT mainly through regulating the mutual solubility/density. Without taking effects of mutual solubility into account, the widely used parachor model in chemical and petroleum engineering fails to predict the IFT for CO2/methane–water pair and n-alkane–water pairs, though it yields a rough estimate for the CO2–water and methane–water pair below the CO2 and methane critical pressures of 7.38 and 4.59 MPa, respectively. However, the parachor model at least considers the effects of solubility in the alkane-rich phase to make it much accurate for n-alkane–CO2 systems. For n-alkane–CO2 pairs, the correlations developed in this work are found to be much less sensitive to the liquid density than the parachor model, being more convenient for practical use. In addition, all the IFTs for the CO2–water pair, methane–water pair, and alkane–CO2 pair can be regressed as a function of density difference of a gas–liquid system with a high accuracy at pressures lower than the critical pressures of either CO2 or methane.

Elemental analysis in a V-Ti-C alloy using electron energy loss spectroscopy

1978 ◽  
Vol 36 (1) ◽  
pp. 552-553
Author(s):  
Hamish L. Fraser
Keyword(s):  
Binary Systems ◽  
Analytical Electron Microscopy ◽  
Scanning Transmission Electron Microscope ◽  
High Temperature Materials ◽  
Transmission Electron ◽  
Interstitial Component ◽  
Analytical Electron ◽  
Scanning Transmission ◽  
Electron Energy Loss

There has been considerable interest in the recent past concerning the application of refractory metal-interstitial systems as high temperature materials. it is important to understand the behavior of the interstitial component, and thus the determination of precipitation processes has been an area of study. in addition to making observations in simple binary systems, there is a need to characterize the changes that occur when other substitutional alloying elements are added. recently, bruemmer has studied the precipitation of carbides in a v-8Ti-c alloy over a range of temperatures. it is particularly interesting to characterize the carbides that precipitate at temperatures when the ti can diffuse rapidly (e.g. 1000°c), and determine not only the structure of the carbide but also perform microchemistry on as fine a scale as possible using analytical electron microscopy. bruemmer used a scanning transmission electron microscope (stem) (jeol jsem 200) coupled with an ortec energy dispersive x-ray analyzer to make measurements of the v:ti ratio in the carbide.

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.

Optimizing conditions for x-ray microchemical analysis in analytical electron microscopy

1978 ◽  
Vol 36 (1) ◽  
pp. 548-549 ◽  
Author(s):  
N. J. Zaluzec
Keyword(s):  
Solid Angle ◽  
Analytical Electron Microscopy ◽  
Incident Beam ◽  
Thin Foil ◽  
Experimental Conditions ◽  
X Ray ◽  
Microchemical Analysis ◽  
Analytical Electron ◽  
Image Position ◽  
Incident Beam Energy

The ultimate sensitivity of microchemical analysis using x-ray emission rests in selecting those experimental conditions which will maximize the measured peak-to-background (P/B) ratio. This paper presents the results of calculations aimed at determining the influence of incident beam energy, detector/specimen geometry and specimen composition on the P/B ratio for ideally thin samples (i.e., the effects of scattering and absorption are considered negligible). As such it is assumed that the complications resulting from system peaks, bremsstrahlung fluorescence, electron tails and specimen contamination have been eliminated and that one needs only to consider the physics of the generation/emission process.The number of characteristic x-ray photons (Ip) emitted from a thin foil of thickness dt into the solid angle dΩ is given by the well-known equation

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.

AEM investigation of ZrO2 solid solution formation in ZrO2/mullite composites

1984 ◽  
Vol 42 ◽  
pp. 408-409
Author(s):  
T. R. Dinger
Keyword(s):  
Solid Solution ◽  
Ion Beam ◽  
Analytical Electron Microscopy ◽  
Transformation Toughening ◽  
Solid Solution Formation ◽  
Solution Formation ◽  
Propagating Crack ◽  
Analytical Electron ◽  
Microcrack Toughening ◽  
Made In

Zirconia (ZrO2) is often added to ceramic compacts to increase their toughness. The mechanisms by which this toughness increase occurs are generally accepted to be those of transformation toughening and microcracking. The mechanism of transformation toughening is based on the presence of metastable tetragonal ZrO2 which transforms to the monoclinic allotrope when stressed by a propagating crack. The decrease in volume which accompanies this transformation effectively relieves the applied stress at the crack tip and toughens the material; microcrack toughening arises from the deflection of a propagating crack around sharply angular inclusions.These mechanisms, however, do not explain the toughness increases associated with the class of composites investigated here. Analytical electron microscopy (AEM) has been used to determine whether solid solution effects could be the cause of this increased toughness. Specimens of a mullite (3Al2O3·2SiO2) + 15 vol. % ZrO2 were prepared by the usual technique of mechanical thinning followed by ion beam milling. All observations were made in a Philips EM400 TEM/STEM microscope fitted with EDXS and EELS spectrometers.

High-resolution x-ray analysis of dislocation networks nn tilt boundaries

1988 ◽  
Vol 46 ◽  
pp. 612-613
Author(s):  
J. R. Michael ◽  
C. H. Lin ◽  
S. L. Sass
Keyword(s):  
Grain Boundaries ◽  
Analytical Electron Microscopy ◽  
Solute Segregation ◽  
X Ray ◽  
Periodic Arrays ◽  
Analytical Electron ◽  
Primary Dislocation ◽  
Tilt Boundaries ◽  
Polycrystalline Solids ◽  
Twist Boundaries

The segregation of solute atoms to grain boundaries in polycrystalline solids can be responsible for embrittlement of the grain boundaries. Although Auger electron spectroscopy (AES) and analytical electron microscopy (AEM) have verified the occurrence of solute segregation to grain boundaries, there has been little experimental evidence concerning the distribution of the solute within the plane of the interface. Sickafus and Sass showed that Au segregation causes a change in the primary dislocation structure of small angle [001] twist boundaries in Fe. The bicrystal specimens used in their work, which contain periodic arrays of dislocations to which Au is segregated, provide an excellent opportunity to study the distribution of Au within the boundary by AEM.The thin film Fe-0.8 at% Au bicrystals (composition determined by Rutherford backscattering spectroscopy), ∼60 nm thick, containing [001] twist boundaries were prepared as described previously. The bicrystals were analyzed in a Vacuum Generators HB-501 AEM with a field emission electron source and a Link Analytical windowless x-ray detector.

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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