Transmission Electron Microscopic Observations of Al3Li and Al3Ti Precipitation in A Rapidly Solidified Al-3Li-0.2Ti ALLOY

1980 ◽  
Vol 38 ◽  
pp. 336-337
Author(s):  
J. E. O’Neal ◽  
K. K. Sankaran ◽  
S. M. L. Sastry
Keyword(s):  
Rapid Solidification ◽  
Metallic Substrate ◽  
Deformation Characteristics ◽  
Phase Decomposition ◽  
Electron Microscopic ◽  
Transmission Electron ◽  
Supersaturated Solid Solutions ◽  
Transmission Electron Microscopic ◽  
Rapidly Solidified ◽  
Microstructural Homogeneity

Rapid solidification of a molten, multicomponent alloy against a metallic substrate promotes greater microstructural homogeneity and greater solid solubility of alloying elements than can be achieved by slower-cooling casting methods. The supersaturated solid solutions produced by rapid solidification can be subsequently annealed to precipitate, by controlled phase decomposition, uniform 10-100 nm precipitates or dispersoids. TEM studies were made of the precipitation of metastable Al3Li(δ’) and equilibrium AL3H phases and the deformation characteristics of a rapidly solidified Al-3Li-0.2Ti alloy.

The Effect of Cu-Macroalloying Additions to Rapidly Solidified NiAl Intermetallic Compound

2000 ◽  
Vol 646 ◽  
Author(s):  
J. Colin ◽  
B. Campillo ◽  
C. Gonzalez ◽  
O. Alvarez-Fregoso ◽  
J. A. Juarez-Islas
Keyword(s):  
Intermetallic Compound ◽  
Room Temperature ◽  
Alloy Composition ◽  
Argon Atmosphere ◽  
Solidification Processing ◽  
Electron Microscopic ◽  
Room Temperature Ductility ◽  
Transmission Electron ◽  
Transmission Electron Microscopic ◽  
Rapidly Solidified

ABSTRACTThe effects of two variables on the NiAl intermetallic compound were studied: 1) copper macroalloying additions and 2) rapid solidification processing. For that purpose, several NiCuAl alloys were vacuum induction melted and rapidly solidified by using a copper wheel, rotating at 15 m/s, under an argon atmosphere. Chemical analysis of as-rapidly solidified ribbons indicated, that four alloy compositions lie in the β-(Ni, Cu)Al field, one alloy composition lie in the boundary of the β-(Ni, Cu)Al/(Ni, Cu)2Al3 fields, one alloy composition lies in the boundary of the β-(Ni, Cu)Al/β-(Ni, Cu)Al + (Ni, Cu)3Al fields and two alloy compositions lie in the β-(Ni, Cu)Al + (Ni, Cu)3Al field. Transmission electron microscopic observations carried out in as-rapidly solidified ribbons, revealed the presence of at least three main structures: i) β-(Ni, Cu)Al, ii) β-(Ni, Cu)Al + martensite (Ni, Cu)Al and iii) (Ni, Cu)3Al + martensite (Ni, Cu)Al. Microhardness Vickers and tensile test data indicated that alloys with a β-(Ni, Cu)Al + martensite (Ni, Cu)Al microstructure have improved room temperature ductility, reaching values of elongation up to 3.28 %.

The blister of porphyria cutanea tarda: A Scanning and Transmission Electron Microscopic study

1986 ◽  
Vol 44 ◽  
pp. 334-335
Author(s):  
Veronika Burmeister ◽  
R. Swaminathan
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Basement Membrane ◽  
Middle Age ◽  
Porphyria Cutanea Tarda ◽  
Minor Trauma ◽  
Electron Microscopic ◽  
Transmission Electron Microscopic Study ◽  
Transmission Electron ◽  
Transmission Electron Microscopic

Porphyria cutanea tarda (PCT) is a disorder of porphyrin metabolism which occurs most often during middle age. The disease is characterized by excessive production of uroporphyrin which causes photosensitivity and skin eruptions on hands and arms, due to minor trauma and exposure to sunlight. The pathology of the blister is well known, being subepidermal with epidermodermal separation, it is not always absolutely clear, whether the basal lamina is attached to the epidermis or the dermis. The purpose of our investigation was to study the attachment of the basement membrane in the blister by comparing scanning with transmission electron microscopy.

TEM comparison of osmium vs osmium with potassium ferricyanide secondary fixatives and the impact of secondary fixative temperature on tissue preservation/contrast quality

1996 ◽  
Vol 54 ◽  
pp. 910-911
Author(s):  
J. W. Horn ◽  
B. J. Dovey-Hartman ◽  
V. P. Meador
Keyword(s):  
Osmium Tetroxide ◽  
Potassium Ferricyanide ◽  
Electron Microscopic ◽  
Transmission Electron ◽  
Microscopic Evaluation ◽  
Cacodylate Buffer ◽  
Transmission Electron Microscopic ◽  
Glutaraldehyde Solution ◽  
Temperature Impact ◽  
The Impact

Osmium tetroxide (OsO4) is a universally used secondary fixative for routine transmission electron microscopic evaluation of biological specimens. Use of OsO4 results in good ultrastructural preservation and electron density but several factors, such as concentration, length of exposure, and temperature, impact overall results. Potassium ferricyanide, an additive used primarily in combination with OsO4, has mainly been used to enhance the contrast of lipids, glycogen, cell membranes, and membranous organelles. The purpose of this project was to compare the secondary fixative solutions, OsO4 vs. OsO4 with potassium ferricyanide, and secondary fixative temperature for determining which combination gives optimal ultrastructural fixation and enhanced organelle staining/contrast.Fresh rat liver samples were diced to ∼1 mm3 blocks, placed into porous processing capsules/baskets, preserved in buffered 2% formaldehyde/2.5% glutaraldehyde solution, and rinsed with 0.12 M cacodylate buffer (pH 7.2). Tissue processing capsules were separated (3 capsules/secondary fixative.solution) and secondarily fixed (table) for 90 minutes. Tissues were buffer rinsed, dehydrated with ascending concentrations of ethanol solutions, infiltrated, and embedded in epoxy resin.

Radial mass analysis of unstained STEM images of molluscan hemocyanins

1990 ◽  
Vol 48 (3) ◽  
pp. 810-811
Author(s):  
M.G. Hamilton ◽  
T.T. Herskovits ◽  
J.S. Wall
Keyword(s):  
Image Analysis ◽  
Hollow Cylinder ◽  
Electron Micrographs ◽  
Side View ◽  
Mass Analysis ◽  
Mass Measurements ◽  
Electron Microscopic ◽  
Transmission Electron ◽  
Transmission Electron Microscopic ◽  
Microscopic Studies

The hemocyanins of molluscs are aggregates of a cylindrical decameric subparticle that assembles into di-, tri-, tetra-, penta-, and larger multi-decameric particles with masses that are multiples of the 4.4 Md decamer. Electron micrographs of these hemocyanins typically show the particles with two profiles: circular representing the cylinder viewed from the end and rectangular representing the side-view of the hollow cylinder.The model proposed by Mellema and Klug from image analysis of a didecameric hemocyanin with the two decamers facing one another with collar (closed) ends outward fits the appearance of side-views of the negatively-stained cylinders. These authors also suggested that there might be caps at the ends. In one of a series of transmission electron microscopic studies of molluscan hemocyanins, Siezen and Van Bruggen supported the Mellema-Klug model, but stated that they had never observed a cap component. With STEM we have tested the end cap hypothesis by direct mass measurements across the end-views of unstained particles.

Formation of coherent twins in YBa2Cu3O7–δ superconductors

1989 ◽  
Vol 4 (4) ◽  
pp. 795-801 ◽  
Author(s):  
C. J. Jou ◽  
J. Washburn
Keyword(s):  
Oxygen Uptake ◽  
Growth Mechanism ◽  
Oxygen Uptake Rate ◽  
Nucleation And Growth ◽  
Electron Microscopic ◽  
Transmission Electron ◽  
Transmission Electron Microscopic ◽  
Twin Formation ◽  
Boundary Model ◽  
Nucleation And Growth Mechanism

A nucleation-and-growth mechanism for the twin formation in YBa2Cu3O7–δ superconductors based on the oxygen uptake rate curve and published transmission electron microscopic observations is proposed together with an oxygen-depleted twin boundary model. The difficulty of reaching stoichiometric YBa2Cu3O7 is explained.

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