Phase identification in SiC whisker reinforced Al2O3-R2O3-based composites

1992 ◽  
Vol 50 (1) ◽  
pp. 152-153
Author(s):  
C.M. Sung ◽  
K.J. Ostreicher ◽  
M.L. Huckabee ◽  
S.T. Buljan
Keyword(s):  
Analytical Electron Microscopy ◽  
Phase Identification ◽  
Reinforced Composites ◽  
Ion Milling ◽  
X Ray ◽  
Binary Oxides ◽  
Analytical Electron ◽  
The Matrix ◽  
Second Phases ◽  
Convergent Beam

A series of binary oxides and SiC whisker reinforced composites both having a matrix composed of an α-(Al, R)2O3 solid solution (R: rare earth) have been studied by analytical electron microscopy (AEM). The mechanical properties of the composites as well as crystal structure, composition, and defects of both second phases and the matrix were investigated. The formation of various second phases, e.g. garnet, β-Alumina, or perovskite structures in the binary Al2O3-R2O3 and the ternary Al2O3-R2O3-SiC(w) systems are discussed.Sections of the materials having thicknesses of 100 μm - 300 μm were first diamond core drilled. The discs were then polished and dimpled. The final step was ion milling with Ar+ until breakthrough occurred. Samples prepared in this manner were then analyzed using the Philips EM400T AEM. The low-Z energy dispersive X-ray spectroscopy (EDXS) data were obtained and correlated with convergent beam electron diffraction (CBED) patterns to identify phase compositions and structures. The following EDXS parameters were maintained in the analyzed areas: accelerating voltage of 120 keV, sample tilt of 12° and 20% dead time.

Phase Identification in TiB2-Ni Composites by Analytical Electron Microscopy

1981 ◽  
Vol 39 ◽  
pp. 138-139
Author(s):  
P. S. Sklad ◽  
J. Bentley ◽  
A. T. Fisher ◽  
G. L. Lehman
Keyword(s):  
Electron Microscopy ◽  
Cutting Tools ◽  
Analytical Electron Microscopy ◽  
High Hardness ◽  
Phase Identification ◽  
Second Phase ◽  
Binder Phase ◽  
Ion Milling ◽  
X Ray ◽  
Analytical Electron

The transition metal diboride TiB2 is characterized by high hardness and high melting point (3253 K) . These properties make this material attractive for applications such as valve components in coal liquefaction plants and cutting tools. Liquid phase hot pressing using nickel as the fluidizing medium allows densification at lower temperatures than when using TiB2 powders alone, but the nickel and TiB2 react to form a complex multiphase microstructure. The purpose of this investigation was to identify the nickel-rich binder phase. The material examined was taken from a cylindrical compact hot pressed at ∼1720 K. During pressing most of the original 15 mol % Ni exuded from the initial mixtures. Specimens 3 mm dia were prepared for analytical electron microscopy (AEM) examination by mechanical lapping followed by ion milling.A typical microstructure of the TiB2-Ni composite examined at 120 kv by conventional transmission electron microscopy (TEM) is shown in Fig. 1. The microstructure is characterized by TiB2 grains bonded by a second phase which was observed at multiple grain intersections. X-ray energy dispersive spectroscopy (EDS) measurements were made using a Philips EM400T/FEG. probe sizes of ∼10 nm dia and probe currents of ∼5 nA were used so that measurements could be made in thin regions of the binder phase, where beam broadening was small. Typical x-ray spectra from an intergranular region and an adjacent TiB2 grain are shown in Fig. 2. The results of standardless quantitative analyses of binder phase spectra indicated a composition (for Z > 11) of at least 95% Ni.

AEM of a Ag-Y-Ba-Cu superconductor precursor material

1993 ◽  
Vol 51 ◽  
pp. 1192-1193
Author(s):  
A. J. Strutt ◽  
M. T. Simnad ◽  
E. Lavernia ◽  
K. S. Vecchio
Keyword(s):  
Melt Spinning ◽  
Analytical Electron Microscopy ◽  
Oxide Phase ◽  
Metallic State ◽  
Ion Milling ◽  
X Ray ◽  
Cu Alloy ◽  
Precursor Material ◽  
Analytical Electron ◽  
Spinning Process

Analytical electron microscopy (AEM) has been used to characterize a Ag-rich superconductor precursor material whose composition (before oxidation) was based on 10 wt.% of a YBa2Cu3 alloy and 90 wt.% Ag, and the same material after an oxidation heat treatment of 690°C for 24 hours. The material had been produced by a melt spinning process as a metallic alloy to permit deformation of the material (in the metallic state) prior to subsequent oxidation to form the ceramic superconducting Y-Ba-Cu oxide phase.The microstructure was characterized using a Philips CM30 AEM, at 300 kV, using specimens thinned to electron transparency by ion-milling. Energy dispersive X-ray spectroscopy (EDX) was performed using the same instrument, with a Link Analytical solid-state X-ray detector with an ultra-thin window.In the as-formed condition, the Y-Ba-Cu alloy phase exists as discrete particles at the triple points of the relatively fine (approx. 250 nm.)

AEM Study on the Phase Transformation of Nickel Silicides in the Ni1-xTax/Si System

2007 ◽  
Vol 124-126 ◽  
pp. 45-48
Author(s):  
J.W. Lee ◽  
Cheol Woong Yang
Keyword(s):  
Thermal Stability ◽  
Phase Transformation ◽  
Analytical Electron Microscopy ◽  
Convergent Beam Electron Diffraction ◽  
Phase Identification ◽  
Post Heat Treatment ◽  
Silicide Layer ◽  
Analytical Electron ◽  
Convergent Beam ◽  
Thermal Stability Of

We investigated the phase transformation and thermal stability of Ni silicides formed in Ni/Si and Ni0.95Ta0.05/Si systems. The sheet resistance values of the silicide in the Ni0.95Ta0.05/Si system were lower than those in Ni/Si system at any temperature. The enhancement of thermal stability is closely related to the phase transformation occurred during post heat-treatment. Microstructure of the phases formed by reaction was investigated by analytical electron microscopy (AEM) and the phase identification of Ni silicide was carried out using convergent beam electron diffraction (CBED) technique. It was found that a Ta rich layer formed on the top of the Ni silicide layer and small amount of Ta dissolved into the silicide layer. By addition of Ta atoms, phase transformation from NiSi to NiSi2 is retarded and thermal stability of Ni silicide is improved.

Sublattice occupancies of Pd in Cu0.5Au0.5−xPdx alloys by ALCHEMI

1989 ◽  
Vol 47 ◽  
pp. 234-235
Author(s):  
J. Bentley ◽  
K. Hisatsune
Keyword(s):  
Analytical Electron Microscopy ◽  
Axial Ratio ◽  
Theoretical Modelling ◽  
X Ray Diffraction ◽  
Ion Milling ◽  
X Ray ◽  
Analytical Electron ◽  
The Face ◽  
Face Centered ◽  
Palladium Content

The composition dependence of the lattice parameters of Cu0.5Au0.5−xPdx (0<x<0.25) alloys with the face-centered tetragonal ordered L10 structure has been measured by X-ray diffraction. The results confirm the behavior reported earlier by Nakahigashi et al. Whereas the unit cell volume decreases monotonically with increasing palladium content, the axial ratio c/a exhibits a maximum at about 4 at. % Pd, corresponding to local minimum and maximum values for a and c, respectively. In theoretical modelling of this behavior it was assumed that Pd atoms were randomly interchangeable with only Au atoms. Several techniques, including the ALCHEMI method, are being used to measure directly the sublattice occupancy of palladium.Electropolishing with various solutions failed to produce good quality specimens for analytical electron microscopy (AEM). Ion milling of specimens previously electropolished with an electrolyte of 10% perchloric acid in acetic acid was more successful. Analyses were performed with Philips EM400T/FEG and CM12/STEM instruments and EDAX 9100/70 and 9900 energy dispersive X-ray microanalysis systems.

A Study on Interfacial Reaction between Electroless Plated Ni-P/Au UBM and Sn-Bi Eutectic Solder Using AEM

2004 ◽  
Vol 449-452 ◽  
pp. 405-408 ◽  
Author(s):  
J.K. Choi ◽  
H.B. Kang ◽  
J.W. Lee ◽  
Seung Boo Jung ◽  
Cheol Woong Yang
Keyword(s):  
Interfacial Reaction ◽  
Analytical Electron Microscopy ◽  
Convergent Beam Electron Diffraction ◽  
Crystallographic Analysis ◽  
Phase Identification ◽  
Primitive Cell ◽  
Under Bump Metallization ◽  
Electron Diffraction Technique ◽  
Analytical Electron ◽  
Convergent Beam

Interfacial reaction between electroless plated Ni-P/Au UBM(Under Bump Metallization and eutectic Sn-58mass%Bi solder was studied by using AEM(Analytical Electron Microscopy). UBM is prepared by the electroless plating of Au (0.15μm ) / Ni-15at%P (7 μm ) on bare Cu substrate, and then it is reacted with Sn-58Bi solder at 220°C for 1 min. The chemical analysis using AEM provided us very consequential information about microstructure of the interface and phases formed. CBED(Convergent Beam Electron Diffraction) technique is used for phase identification of intermetallic compounds. In this study, the AEM results indicate that Ni3Sn is formed at the P-rich Ni layer/Ni3Sn4 interface by crystallographic analysis. The measured primitive cell volume(104.10 Å3)of this phase is close to the Ni3Sn(103.19 Å3) rather than Ni2SnP(235.24 Å3).

Processing and Microstructural Characterization of TiB2 Liquid Phase Sintered with Ni and Ni3Al

1983 ◽  
Vol 24 ◽  
Author(s):  
P. Angelini ◽  
P. F. Becher ◽  
J. Bentley ◽  
C. B. Finch ◽  
P. S. Sklad
Keyword(s):  
Analytical Electron Microscopy ◽  
Phase Diagram Data ◽  
Microstructural Characterization ◽  
Convergent Beam Electron Diffraction ◽  
Intergranular Phase ◽  
X Ray ◽  
Analytical Electron ◽  
Convergent Beam ◽  
Electron Energy Loss

ABSTRACTAn Analytical Electron Microscopy investigation of TiB2 hot-pressed and pressureless sintered with Ni revealed the presence of Ni3B and tau intergranular phase, respectively. Convergent Beam Electron Diffraction (CBED) was used for crystal structure determination and compositions were determined by quantitative x-ray Energy Dispersive Spectroscopy (EDS) and Electron Energy Loss Spectroscopy (EELS). The phase analyses were compared with phase diagram data. An evaluation was also made of TiB2 hot pressed with Ni3Al. Quantitative EDS and EELS microanalysis indicated a Ni,Al type boride tau (Cr23C6 type) intergranular phase.

Convergent-beam diffraction and x-ray analysis of the lamellar structure in the Dayton meteorite

1986 ◽  
Vol 44 ◽  
pp. 698-699
Author(s):  
J. A. Kowalik
Keyword(s):  
Energy Dispersive Spectrometry ◽  
Analytical Electron Microscopy ◽  
Iron Meteorites ◽  
Cooling History ◽  
X Ray ◽  
Lamellar Morphology ◽  
Structure Changes ◽  
Analytical Electron ◽  
Convergent Beam ◽  
Beam Diffraction

The phase transformation resulting in a lamellar morphology found in the iron meteorite Dayton (18 wt% Ni-Fe) has been investigated using analytical electron microscopy (AEM). The transformation is unique to the Dayton meteorite since in other iron meteorites of similar composition and cooling history, only the classical Widmanstätten structure is present consisting of ferritic (α-BCC) plates precipitating on the (111) planes of the prior austenite (γ-FCC). However, in some areas of Dayton, the structure changes from the classical Widmanstätten pattern to a lamellar morphology. As a first step in understanding the mechanisms of the precipitation reactions, convergent beam electron diffraction (CBED) and x-ray energy dispersive spectrometry (XEDS) have been used to examine the crystallographic orientation and composition of the α/γ interface of the Widmanstätten and lamellar morphology.

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

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.

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