Boundary segregation

Application of AES to zirconia ceramics has been reported by Moser et al. [2.146]. Elemental maps of Al and Si demonstrate the grain boundary segregation of small impurities of silica and alumina in these ceramics. 

It is claimed that since S, Ca and A1 will be present as precipitates they would not in general be detected as grain boundary segregants and their ineffectiveness is indicated by the brackets in equation 8.10. Lea and Hondros do not consider the possible roles of carbon or nitrogen in the cracking of their steels, but from the data obtained phosphorous had the most deleterious effects. 

Figure 1.10. Grain boundary segregation in neutron irradiated weld from Russian WER 440 nuclear reactor position of individual atom is represented by a dot. Enrichment of P, Mo and Mn atoms are visible at boundary (arrowed), and three 2 nm diameter Cu-enriched precipitates near the boundary are also visible. (Reproduced by permission of Thomson and Miller 2000.)...

If the composition of the outermost layer is different from that of the bulk (for example, as a result of surface or grain boundary segregation), a different approach has to be made. For example, if a partial overlayer of element A of fractional coverage 9a covers a substrate of element B, the spectrum contains three contributions that from the overlayer, that from the exposed part of the substrate, and that from the covered part of the substrate. 

Depth Profiling. The quantitative interpretation of AES data requires a knowledge of the distribution of the grain boundary segregants both laterally on the... 

A careful, quantitative study on grain boundary segregation, boron segregation in austenitic stainless steels of types 316L (with 206 at. p.p.m. of boron, and with <5 at. p.p.m. of boron) and Mo-free 316L (75 at. p.p.m. boron), has been reported by Karlsson, Norden, and Andren36 using a combination of TEM, FIM, AP and IAP techniques. Concen-... 

Nakatani, K., Nagayama, H., Yoshida, H., Yamamoto, T., and Sakuma, T., The effect of grain boundary segregation on superplastic behavior in cation-doped 3Y-TZP , Scrlpta Mater., 2003, 49, 791-5. 

K. Przybyiski, A. J. Garratt-Reed, and G. J. Yurek, Grain-boundary Segregation of Yttrium in Chromia Scale, Journal of Electrochemical Section, 135,1988, p.509. 

Grain Boundary Segregation of Impurity in Polycrystalline Silicon... 

For the SoG-Si polycrystalline silicon, both the XGB and X are far less than unity. Furthermore, if the impurities follow Henry s law, e.g., (13.6), the effect of the excess Gibbs energy on the grain boundary segregation can be neglected. Equation (13.20) may, thus, be simplified to pcpc... 

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