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The liquidus projection at the boron-rich corner of the B-Fe-U phase diagram is proposed based on powder X-ray diffraction measurements, heating curves, and scanning electron microscopy observations, complemented with both energy dispersive X-ray spectroscopy and electron probe microanalysis. Evidence for six ternary reactions is presented, the corresponding 12 monovariant lines are drawn, and the nature and location of the ternary reactions are given. The ternary compounds existing in this region of the B-Fe-U ternary phase diagram, UFeB and UFeB, were confirmed to be formed by ternary peritectic reactions, yet UFeB has a considerably larger primary crystallization field, which points to an easier preparation of single crystals of this compound, when compared with UFeB. [ABSTRACT FROM AUTHOR]

Since 1987, the Manila clam Ruditapes philippinarum has been regularly affected by the brown ring disease (BRD), an epizootic caused by the bacterium Vibrio tapetis. This disease is characterized by the development of a brown deposit on the inner face of valves. While most of the clams die from the BRD infection, some of them are able to recover by mineralizing a new repair shell layer, which covers the brown deposit by a process of encapsulation. The purpose of this work was to study the organic matrix of the shells of Manila clams in the inner shell layer before, during and after the brown deposit and during the shell repair process by confocal Raman micro-spectrometry and wavelength dispersive spectrometry (WDS) microprobe. In addition, the organic matrix of the repaired shell layer was extracted and quantified, by using standard biochemical shell matrix extractions protocols. The brown deposit exhibited high luminescence intensity in Raman spectra, and an increase of S, C, Sr (forming two peaks) and a decrease of Ca, Na concentrations (% w/ w), using WDS microprobe mapping and cross-sectional transects. The signature of these trace elements was similar to that recorded on periostracal lamina (% w/ w). The high S concentration likely corresponds to the presence of a high amount of sulfated organic compounds. Interestingly, on cross-sectional transects, before the brown deposit, a thin layer of the shell showed also a high luminescence, which may suggest that this layer is modified by bacteria. After the brown deposit, at the beginning of the shell repair process, the luminescence and the S concentration remain high, before declining the level found in non-BRD-affected shells. Quantification of the organic matrix shows that the shell repair layer zone is significantly different from non-BRD-affected shell layer, in particular with a much higher amount of insoluble matrix. [ABSTRACT FROM AUTHOR]

Phase relations in the ternary system N-Ni-Ti have been established experimentally for the 900 °C isothermal section assisted by thermodynamic modeling. Phase equilibria are characterized by an appreciable amount of up to ≅11 at. % N dissolved in the octahedral interstices of the crystal structure of Ti2Ni. Two-phase equilibria are formed at 900 °C among the pairs Ti2N + Ti2NiNx, TiN1-x + Ti2NiNx, TiN1-x + TiNi1-x, and TiN1-x + Ni(Ti)x. The investigation is based on X-ray powder diffraction, metallography, scanning electron microscopy, and electron probe microanalysis techniques on about 50 alloys, which were prepared by arc melting or high-frequency levitation melting of appropriate blends of Ti,Ni-powders with TiN used to introduce nitrogen. Key experiments related to the N solubility in the Ti2Ni phase have been triggered by an interactively performed thermodynamic modeling. The experimental results are in fine agreement with the thermodynamic calculation. [ABSTRACT FROM AUTHOR]

Wavelength-dispersive electron-probe microanalysis of transition metal carbide and nitride diffusion couples was investigated as a tool to quantitatively determine portions of phase diagrams. In crosssections, diffusion couples generally show a sequence of several phases composed of crystallites with different orientations and hardness values. Thus, the polishing procedure can adversely affect the accuracy of the analysis due to creation of an uneven surface (relief effect). In addition, as a result of the polishing process the edges of the samples are rounded so that the concentration at the original sample surface is difficult to measure. The most rapid and straightforward procedure to detect influences of the relief effect is a plot of the non-normalized analytical total vs. distance, even where the concentration profile is discontinuous at the interface between phase bands. It is shown that careful experimental preparation, as well as the application of restricted diffusion geometry, has several advantages for establishing phase diagrams. [ABSTRACT FROM AUTHOR]