An Automated Laboratory Apparatus for the Production of Rapidly Solidified Submicron Powders

1981 ◽  
Vol 8 ◽  
Author(s):  
Julius Perel ◽  
John F. Mahoney ◽  
Scott Taylor ◽  
Zef Shanfield ◽  
Carlos Levi
Keyword(s):  
Electron Microscope ◽  
Single Crystal ◽  
Liquid State ◽  
Metastable Phases ◽  
Liquid Droplets ◽  
Laboratory Apparatus ◽  
Material Scientist ◽  
Automated Instrument ◽  
Rapidly Solidified

ABSTRACTThe Electrohydrodynamic (EHD) method of spraying fine liquid droplets from a liquid state, in a vacuum environment, was developed and used to produce amorphous, microcrystalline, single crystal, bicrystalline and tricrystalline powders. Studies of these powders have contributed towards increasing the knowledge of extended solubility, nucleation, metastable phases, undercooling effects, etc. Coatings and films have been produced by collecting the liquid droplets before solidification. An automated instrument based upon the EHD method, the Micro-Particle Processor, is computer operated and allows a material scientist not completely acquainted with the EHD process to perform sophisticated experiments on materials of his choosing. Electron transparent powders close to 3μm and large powders up to l00μm have been collected and observed. Cooling rates above 107K/s have been achieved. Applications using powders include: new alloy compositions, use as AEM standards, in-situ remelt experiments in the electron microscope, etc.

In situ transmission electron microscope measurements of solid Al-solid Pb and solid Al-liquid Pb surface-energy anisotropy in rapidly solidified Al-5% Pb (by mass)

1987 ◽  
Vol 414 (1847) ◽  
pp. 499-507 ◽  
Keyword(s):  
Electron Microscope ◽  
Melting Point ◽  
Surface Energy ◽  
Transmission Electron Microscope ◽  
Room Temperature ◽  
Transmission Electron ◽  
Increasing Temperature ◽  
Rapidly Solidified ◽  
Al Matrix

Alloys of Al-5% Pb and Al-5% Pb-0.5% Si (by mass) have been manufactured by rapid solidification and then examined by transmission electron microscopy. The rapidly solidified alloy microstructures consist of 5-60 nm Pb particles embedded in an Al matrix. The Pb particles have a cube-cube orientation relation with the Al matrix, and are cub-octahedral in shape, bounded by {100} Al, Pb and {111} Al, Pb facets. The equilibrium Pb particle shape and therefore the anisotropy of solid Al-solid Pb and solid Al-liquid Pb surface energies have been monitored by in situ heating in the transmission electron microscope over the temperature range between room temperature and 550°C. The ani­sotropy of solid Al-solid Pb surface energy is constant between room temperature and the Pb melting point, with a {100} Al, Pb surface energy about 14% greater than the {111} Al, Pb surface energy, in good agreement with geometric near-neighbour bond energy calculations. The {100} AI, Pb facet disappears when the Pb particles melt, and the anisotropy of solid Al-liquid Pb surface energy decreases gradually with increasing temperature above the Pb melting point, until the Pb particles become spherical at about 550°C.

In-situ tensile testing of single-crystal molybdenum-alloy fibers with various dislocation densities in a scanning electron microscope

2011 ◽  
Vol 27 (3) ◽  
pp. 508-520 ◽  
Author(s):  
Kurt E. Johanns ◽  
Andreas Sedlmayr ◽  
P. Sudharshan Phani ◽  
Reiner Mönig ◽  
Oliver Kraft ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Single Crystal ◽  
Tensile Testing ◽  
Molybdenum Alloy ◽  
Dislocation Densities ◽  
Image Position ◽  
Scanning Electron ◽  
In Situ Tensile Testing

Abstract

Preparation of Thin Single Crystal Silicon Substrates for in situ Electron Microscope Studies

1973 ◽  
Vol 31 ◽  
pp. 120-121
Author(s):  
J. S. Maa ◽  
J. I. Lee ◽  
Thos. E. Hutchinson
Keyword(s):  
Electron Microscope ◽  
Single Crystal ◽  
Ion Beam ◽  
Single Crystal Silicon ◽  
Thin Film Deposition ◽  
Film Deposition ◽  
Micro Milling ◽  
Crystal Silicon ◽  
Etching Technique

The in-situ electron microscope technique has been shown to be a powerful method for understanding the nucleation and growth of thin films formed both by vacuum vapor deposition and ion beam sputter-deposition. Single crystal silicon which has only been chosen as substrate for thin film deposition outside the electron microscope has now been prepared in a form suitable for in-situ deposition.The method of the preparation of thin silicon substrate is a combination of jet chemical etching and modified ion beam thinning. A specimen of thickness roughly 0.010 inch is first etched from both sides by the jet etching technique. After jet etching, it is transferred to the Commonwealth Scientific ion micro-milling instrument and bombarded from both sides with Argon ion beam. A pin hole occurs in the center of the specimen after about 30 minutes of ion bombardment.

Radiation Effects in Zircon, Hafnon, and Thorite: Implications for Pu Disposal

1998 ◽  
Vol 540 ◽  
Author(s):  
A. Meldrum ◽  
S.J. Zinkle ◽  
L.A. Boatner ◽  
M. Wu ◽  
R. Mu ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Optical Absorption ◽  
Single Crystal ◽  
Microstructural Evolution ◽  
Transmission Electron Microscope ◽  
Nd:Yag Laser ◽  
Radiation Effects ◽  
New Model ◽  
Transmission Electron

AbstractSynthetic ZrSiO4, HfSiO4, and ThSiO4 single-crystal specimens were irradiated by 800 keV Kr+ ions, and the microstructural evolution was observed in-situ in a transmission electron microscope. All three compounds were found to become amorphous up to temperatures in excess of 600°C. Using a new model, the activation energies for annealing were found to be in the range of 3.1 to 3.6 eV for these compounds. At temperatures above 600°C, the orthosilicates were observed to decompose into the component oxides (e.g., tetragonal ZrO2 + amorphous SiO2 in the case of zircon). A single-crystal zircon specimen was also irradiated with a pulsed picosecond Nd:YAG laser operated at 355 nm, and the resulting microstructure was investigated by optical absorption, SEM, AFM, and TEM techniques.

Direct observations of the sintering of silver nanoparticles on single crystal copper by in-situ uhv tem

1997 ◽  
Vol 501 ◽  
Author(s):  
M. Yeadon ◽  
J. C. Yang ◽  
R. S. Averback ◽  
J. W. Bullard ◽  
J. M. Gibson
Keyword(s):  
Silver Nanoparticles ◽  
Electron Microscope ◽  
Single Crystal ◽  
Epitaxial Film ◽  
Substrate Surface ◽  
Silver Particles ◽  
Single Crystal Copper ◽  
Direct Observations ◽  
Transmission Electron

ABSTRACTUsing a novel ultrahigh vacuum (UHV) transmission electron microscope with in-situ UHV sputtering attachment we have studied the sintering of copper and silver nanoparticles with single crystal copper substrates. Copper and silver particles deposited on (001) copper initially assume random orientations. Upon annealing, however, the particles reorient and assume an epitaxial orientation with the substrate. In the case of copper on copper, homoepitaxy occurs by a process involving sintering and grain growth. In the case of silver on copper, we have observed the particles to wet the substrate surface and sinter to form a thin epitaxial film with the orientation relationship (111)Ag // (001)Cu, [110]Ag // [110]Cu.

Structure of Palladium Single-Crystal Films Prepared by Flash Evaporation onto (001) NaCl Substrates

1970 ◽  
Vol 28 ◽  
pp. 456-457
Author(s):  
L. E. Murr ◽  
G. Wong
Keyword(s):  
Single Crystal ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
High Rate ◽  
Flash Evaporation ◽  
Optimum Load ◽  
Single Crystal Films ◽  
Crystal Films ◽  
A Current

Palladium single-crystal films have been prepared by Matthews in ultra-high vacuum by evaporation onto (001) NaCl substrates cleaved in-situ, and maintained at ∼ 350° C. Murr has also produced large-grained and single-crystal Pd films by high-rate evaporation onto (001) NaCl air-cleaved substrates at 350°C. In the present work, very large (∼ 3cm2), continuous single-crystal films of Pd have been prepared by flash evaporation onto air-cleaved (001) NaCl substrates at temperatures at or below 250°C. Evaporation rates estimated to be ≧ 2000 Å/sec, were obtained by effectively short-circuiting 1 mil tungsten evaporation boats in a self-regulating system which maintained an optimum load current of approximately 90 amperes; corresponding to a current density through the boat of ∼ 4 × 104 amperes/cm2.

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.

In situ Tensile Experiments at Low Temperatures on Niobium Single Crystals by H.V.E.M.

1975 ◽  
Vol 33 ◽  
pp. 58-59
Author(s):  
F. H. Louchet ◽  
L. P. Kubin
Keyword(s):  
Electron Microscope ◽  
Transition Temperature ◽  
Low Temperature ◽  
Slip System ◽  
Low Temperatures ◽  
Tensile Axis ◽  
Image Intensifier ◽  
Screw Dislocations ◽  
Source Operation

Experiments have been carried out on the 3 MeV electron microscope in Toulouse. The low temperature straining holder has been previously described Images given by an image intensifier are recorded on magnetic tape.The microtensile niobium samples are cut in a plane with the two operative slip directions [111] and lying in the foil plane. The tensile axis is near [011].Our results concern:- The transition temperature of niobium near 220 K: at this temperature and below an increasing difference appears between the mobilities of the screw and edge portions of dislocations loops. Source operation and interactions between screw dislocations of different slip system have been recorded.

In-situ electrical-resistivity measurements in the high-voltage electron microscope

1978 ◽  
Vol 36 (1) ◽  
pp. 68-69
Author(s):  
W. E. King
Keyword(s):  
Electrical Resistivity ◽  
Electron Microscope ◽  
High Voltage ◽  
Resistivity Measurements ◽  
Voltage Electron ◽  
High Voltage Electron Microscope ◽  
High Voltage Electron ◽  
Wide Range ◽  
Helium Gas

A side-entry type, helium-temperature specimen stage that has the capability of in-situ electrical-resistivity measurements has been designed and developed for use in the AEI-EM7 1200-kV electron microscope at Argonne National Laboratory. The electrical-resistivity measurements complement the high-voltage electron microscope (HVEM) to yield a unique opportunity to investigate defect production in metals by electron irradiation over a wide range of defect concentrations.A flow cryostat that uses helium gas as a coolant is employed to attain and maintain any specified temperature between 10 and 300 K. The helium gas coolant eliminates the vibrations that arise from boiling liquid helium and the temperature instabilities due to alternating heat-transfer mechanisms in the two-phase temperature regime (4.215 K). Figure 1 shows a schematic view of the liquid/gaseous helium transfer system. A liquid-gas mixture can be used for fast cooldown. The cold tip of the transfer tube is inserted coincident with the tilt axis of the specimen stage, and the end of the coolant flow tube is positioned without contact within the heat exchanger of the copper specimen block (Fig. 2).

A TEM study of the microstructure of avian eggshells

1992 ◽  
Vol 50 (2) ◽  
pp. 1102-1103
Author(s):  
S. Q. Xiao ◽  
S. Baden ◽  
A. H. Heuer
Keyword(s):  
Electron Microscope ◽  
Calcium Carbonate ◽  
Nucleation And Growth ◽  
Growth Mechanisms ◽  
Shell Surface ◽  
Thin Sections ◽  
Polycrystalline Metals ◽  
Transmission Electron ◽  
Nucleation And Growth Mechanisms

The avian eggshell is one of the most rapidly mineralizing biological systems known. In situ, 5g of calcium carbonate are crystallized in less than 20 hrs to fabricate the shell. Although there have been much work about the formation of eggshells, controversy about the nucleation and growth mechanisms of the calcite crystals, and their texture in the eggshell, still remain unclear. In this report the microstructure and microchemistry of avian eggshells have been analyzed using transmission electron microscope (TEM) and energy dispersive spectroscopy (EDS).Fresh white and dry brown eggshells were broken and fixed in Karnosky's fixative (kaltitanden) for 2 hrs, then rinsed in distilled H2O. Small speckles of the eggshells were embedded in Spurr medium and thin sections were made ultramicrotome.The crystalline part of eggshells are composed of many small plate-like calcite grains, whose plate normals are approximately parallel to the shell surface. The sizes of the grains are about 0.3×0.3×1 μm3 (Fig.l). These grains are not as closely packed as man-made polycrystalline metals and ceramics, and small gaps between adjacent grains are visible indicating the absence of conventional grain boundaries.

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