Microstructural analysis

A systematic study of the Yb-Pd-Ge system (fig. 114) has been performed by Seropegin et al. (1994) employing X-ray phase analysis, microstructural and local X-ray spectral analyses of 152 samples which were arc melted and annealed at 870 K for 600 h. The existenee of one ternary compound was confirmed and formation of nine other ternary phases was observed for the first time. The purity of the metals used for the synthesis of the alloys was Yb 99.98 mass%, Pd and Ge 99.99 mass%. 

ASM Handbook. ASM International http //products.asmintemational.org/hbk/index.jsp (accessed March 27, 2011). The ASM Handbook comprises 21 volumes providing major reference information to industry about mining extraction, metallurgical processing and fabrication of metals testing, inspection, and failure analysis microstructural analysis and materials characterization corrosion, and wear phenomena in machinery and eqnipment, some of it used in the mining industry. 

Phase diagrams have been determined for sections of the i -Bi-Se R = Ce, Sm, Tm) systems as a function of composition and temperature, through powder X-ray diffraction, differential thermal analysis, microstructural analysis, and microhardness measurements. 

In spite of the compounding of errors to which it is subject, the foregoing method was the best procedure for measuring reactivity ratios until the analysis of microstructure became feasible. Let us now consider this development. 

Microstructural analysis revealed branched cracks running across the metal grains (transgranular) originating on the external surface. 

Microstructural examinations revealed branched, transgranular cracks originating on the external surface (treated cooling water). Analysis of material covering the crack surfaces revealed the presence of chlorine. 

The second misconception involves the perception of what constitutes a defect. A defect is not simply a visually observable discontinuity such as a hole, lap, or seam in a component. Defects, from a failure-analysis standpoint, may also be such things as a high residual stress that may lead to cracking or unfavorable microstructures that can lead to either... 

Atomic structure and Microstructural analysis of solid materials, providing high lateral resolution... 

Analysis of surface crystallography and microstructure surface cleanliness... 

The uniqueness and desirability of EELS is realized when it is combined with the power of a TEM or STEM to form an Analytical Electron Microscope (AEM). This combination allows the analyst to perform spatially resolved nondestructive analysis with high-resolution imaging (< 3 A). Thus, not oiJy can the analyst observe the microstructure of interest (see the TEM article) but, by virtue of the focusing ability of the incident beam in the electron microscope, he or she can simultaneously analyze a specific region of interest. Lateral spatial resolutions of regions as small as 10 A in diameter are achievable with appropriate specimens and probe-forming optics in the electron microscope. 

The first detailed book to describe the practice and theory of stereology was assembled by two Americans, DeHoff and Rhines (1968) both these men were famous practitioners in their day. There has been a steady stream of books since then a fine, concise and very clear overview is that by Exner (1996). In the last few years, a specialised form of microstructural analysis, entirely dependent on computerised image analysis, has emerged - fractal analysis, a form of measurement of roughness in two or three dimensions. Most of the voluminous literature of fractals, initiated by a mathematician, Benoit Mandelbrot at IBM, is irrelevant to materials science, but there is a sub-parepisteme of fractal analysis which relates the fractal dimension to fracture toughness one example of this has been analysed, together with an explanation of the meaning of fractal dimension , by Cahn (1989). 

Exner, H.E, and Hougardy, H.P. (1988) Quantitative Image Analysis of Microstructures (DGM Informationsgesellschaft Verlag, Oberursel). 

J Electron microprobe analysis. The instrument which I shall introduce here is, in my view, the most important development in characterisation since the 1939-1945 War. It has completely transformed the study of microstructure in its compositional perspective. 

Y.Zheng, W.M.Stobbs, The tweed microstructure in B2 Ni-rich Ni-Al alloys, in Electron Microscopy and Analysis 95, ed. D.Chems, Inst Phys.Conf Ser. No 147, Inst.of Physics (1995), p.353... 

The analysis of XRPD patterns is an important tool studying the crystallographic structure and composition of powder compounds including the possibility to study deviation from ideal crystallinity, i.e. defects. Looking at an X-ray powder diffractogram the peak position reflects the crystallographic symmetry (unit cell size and shape) while the peak intensity is related to the unit cell composition (atomic positions). The shape of diffraction lines is related to defects , i.e. deviation from the ideal crystallinity finite crystallite size and strain lead to broadening of the XRPD lines so that the analysis of diffraction line shape may supply information about sample microstructure and defects distribution at the atomic level. 

The study of the peak shape gives important information relative to the microstructure of the sample even when it is included in the Rietveld code. Actually, in order to perform the Warren-Averbach analysis or other mi-crostructural studies, it is not necessary to use the Rietveld analysis, but it is often sufficient to operate with less complex, non-structural peak fitting procedures. 

There is, in any case, an important advantage in using the Rietveld analysis, which is the possibility of quanti-f5ing the phase to which we are ascribing the microstructure properties. 

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