PHASE IDENTIFICATION AND MICROSTRUCTURE ANALYSIS OF INTERFACE Al-Si∕SiC COMPOSITES

Image shifts in out-of-focus dark field images have been used in the past to determine, for example, epitaxial relationships in thin films. A recent extension of the use of dark field image shifts has been to out-of-focus images in conjunction with stereoviewing to produce an artificial stereo image effect. The technique, called through-focus dark field electron microscopy or 2-1/2D microscopy, basically involves obtaining two beam-tilted dark field images such that one is slightly over-focus and the other slightly under-focus, followed by examination of the two images through a conventional stereoviewer. The elevation differences so produced are usually unrelated to object positions in the thin foil and no specimen tilting is required.In order to produce this artificial stereo effect for the purpose of phase separation and identification, it is first necessary to select a region of the diffraction pattern containing more than just one discrete spot, with the objective aperture.

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

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100121168 ◽

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.

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Applications of SEM/EDXA in cement clinker investigation

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100177489 ◽

1990 ◽

Vol 48 (4) ◽

pp. 870-871

Author(s):

Arezki Tagnit-Hamou ◽

Shondeep L. Sarkar

Keyword(s):

Mineralogical Composition ◽

Physicochemical Characteristics ◽

Cement Clinker ◽

Accurate Information ◽

Phase Identification ◽

History Of ◽

Bulk Chemical ◽

Resolution Imaging ◽

Proven Method ◽

Instantaneous Chemical

All the desired properties of cement primarily depend on the physicochemical characteristics of clinker from which the cement is produced. The mineralogical composition of the clinker forms the most important parameter influencing these properties.Optical microscopy provides reasonably accurate information pertaining to the thermal history of the clinker, while XRDA still remains the proven method of phase identification, and bulk chemical composition of the clinker can be readily obtained from XRFA. Nevertheless, all these microanalytical techniques are somewhat limited in their applications, and SEM/EDXA combination fills this gap uniquely by virtue of its high resolution imaging capability and possibility of instantaneous chemical analysis of individual phases.Inhomogeneities and impurities in the raw meal, influence of kiln conditions such as sintering and cooling rate being directly related to the microstructure can be effectively determined by SEM/EDXA. In addition, several physical characteristics of cement, such as rhcology, grindability and hydraulicity also depend on the clinker microstructure.

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The Russian ruble crisis of December 2014

Voprosy Ekonomiki ◽

10.32609/0042-8736-2016-5-66-86 ◽

2016 ◽

pp. 66-86

Author(s):

A. Obizhaeva

Keyword(s):

Microstructure Analysis ◽

Future Market ◽

Effective Response ◽

Large Order ◽

Short Period ◽

The Face ◽

Front Running ◽

Futures And Options

The paper presents a microstructure analysis of the crash of the Russian ruble in mid-December 2014. The author shows that the market break probably happened due to the execution of a large order that converted Russian rubles into U.S. dollars over a short period of a few days. Expirations of futures and options as well as possible front-running could have exacerbated the collapse of the Russian currency. The paper discusses measures taken by the Moscow Exchange and Bank of Russia during the episode and makes several recommendations to prevent a repetition of the similar events and provide an effective response in the face of future market breaks.

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