Compositional mapping, microstructure

Microstructural Analysis. After sintering, the samples were examined by SEM. Both fired and fracture surfaces were examined uncoated. Samples were also mounted in epoxy and polished with diamond paste to 1/zm. These samples were then used for compositional mapping or coated with Au and examined in the SEM. 

Compositional Mapping. A new technique of compositional mapping by electron probe microanalysis Q) has been applied to characterize the compositional microstructure of the samples. Electron probe compositional mapping involves the use of computer-aided microscopy for the construction of images in which the displayed gray scale is related to the true composition of the specimen and not merely to X-ray intensity. 

The microstructure and thickness of the oxide layers formed after exposure to atmospheric air at 1400 C was studied for both ZS and ZSC samples, which were cut and polished for observation in the SEM. Figure 6 shows a micrograph and compositional maps for a ZS sample annealed for 1 hour. The outer. Si and O rich layer can be concluded to be SiOi, while the intermediate layer, which is O rich and B poor, is Zr02. Similar conclusions can be drawn from Figure 7, which represents compositional maps for a ZSC sample annealed for 24h. Again, the outer layer is mainly composed of Si02, and an intermediate layer of ZrO separates the fonner layer and the bulk interior of the sample. 

The high sensitivity of detectors allows the study by transmission or reflection of very small samples such as those that can be examined under an optical microscope. The focusing of the beam upon a zone of only a few micrometres enables to obtain a chemical map which is linked to the composition of the sample if it presents a microstructure. The instrumentation includes a spectrometer coupled with an observation microscope (Figure 10.19). 

From an economic viewpoint, the classical determination of alloy phase diagrams is a laborious process, involving alloy preparation and heat treatment, compositional, structural, and microstructural analysis (and, even then, not yielding reliable phase boundary information at low temperatures due to kinetic limitations). While this investment is justified for alloys of major technical importance, the need for better economics has driven an effort to use alternative methods of phase discovery such as multiple source, gradient vapor deposition or sputter deposition followed by automated analysis alternatively, multicomponent diffusion couples are used to map binary or ternary alloy systems structurally and by properties (see Section 6). These techniques have been known for decades, but they have been reintroduced more recently as high-efficiency methodologies to create compositional libraries by a combinatorial approach, inspired perhaps by the recent, general introduction of combinatorial methods in chemistry. 

Nowadays, electron microscopy has evolved to allow the determination of polymer morphology and composition to be mapped as a function of time in several physical conditions. In particular, in situ microscopy can provide morphological structure and also information on the dynamic changes in properties present in microstructures during synthesis, phase transformations, and physical tests [31]. 

In P-Tref/SEC cross-fractionation, copolymer chains are first fractionated according to comonomer composition into a series of fractions using P-Tref. Each fraction is then analyzed using SEC to obtain its MWD. P-Tref/SEC is a very powerful cross-fractionation technique because it provides information on the bivariate comonomer composition and MWD. Although the process is still time-consuming, the information obtained with P-Tref/SEC crossfractionation provides an almost complete map of chain microstructures. This cross-fractionation technique has been used for various ethylene/1-olefin copolymers (1-butene, 1-hexene, 1-octene, and l-pentene-4-methyl). 

It is possible to make up microstructure maps, which separate the regions of initial compositions leading to different final states (resulting single-phase alloy or a two-phase zone) in the phase diagram. 

Figure 2 shows the overall microstructure of the polished cross-section of the pseudowollastonite pellet after one month immersion in simulated body fluid and its relevant X-ray maps for silicon, calcium and phosphorous elements. This compositional microcharacterisation of the interface showed that the reaction zone was composed of two chemically dissimilar layers formed on the pseudowollastonite surface. The outer layer, with an average thickness of about 10 pm, was composed of a Ca0/P205-rich phase, identified as... 

The authors stress the advantages of pre-resonance intensity enhancement effect accompanying the FT-Raman measurements allowing to detect carotenoids even in trace amounts with simultaneous elimination of background fluorescence of the plant sample. These special advantages of FT-Raman spectroscopy applied to 2D Raman mappings enabled to illustrate the distribution of individual plant carotenoids independently from each other in the same sample [4]. Furthermore, the high potential of FT-Raman microspectroscopy to obtain detailed information about microstructure and chemical composition of fennel fruits, chamomile inflorescence, and curcuma roots was demonstrated [11]. 

Binary phase diagrams are maps that represent the relationships between temperature and the compositions and quantities of phases at equilibrium, which influence the microstructure of an alloy. Many microstructures develop from phase transformations, the changes that occur when the temperature is altered (typically upon cooling). This may involve the transition from one phase to another or the appearance or disappearance of a phase. Binary phase diagrams are helpful in predicting phase transformations and the resulting microstructures, which may have equilibrium or nonequilibrium character. 

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