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Solid dissolution : effect of mass transport-precipitation coupling

出版	Atomic Energy Of Canada Limited, 1986
URL	http://books.google.com.hk/books?id=g0lq0AEACAAJ&hl=&source=gbs_api

註釋Steam-formed oxides grown on zr-1nb, zr-2.5nb and zr-20nb (annealed, quenced and quenched then aged) specimens, before and after reaction with d20 vapour and d2 (10-3) torr, 320 degrees c, 5 days) have been studied by x-ray photoelectron spectroscopy (xps) and secondary ion mass spectrometry (sims). preliminary results suggest that the oxide thickness decreases in the order: 20 percent > 2.5 percent > 1 percent, but the total deuterium ingress decreases in the opposite order,i.e. 1 percent > 2.5 percent > 20 percent. in general, oxide thickness also decreases in the order: quenched > annealed > aged material, but the total ingress of deuterium was rather scattered and the annealed samples appeared to absorb the least d2. xps spectra obtained for the zr-20nb samples (regardless of thermal treament), from the aged sample (before sputtering) and from the quenched samples (after 4 hours sputtering) consistently exhibited the lowest oh-/od- and h20/d20 peak intensity. the oxides formed on the 20 percent nb alloys, except that aged, showed more evidence for oxide dissolution following reaction with d2 than the 1 percent and the 2.5 percent alloys, with nb205 preferentially reduced. when the 20 percent nb alloy was heated in ar, instead of d2, the oxides dissolved only slightly. these results imply that d2 in the annulus gas may enter primarily at beta-phase boundaries, and that d2 assists in "breaking down" the nb-rich oxide. in addition, the deuterium content of the metals increased slightly for the 1 percent nb and the 2.5 percent nb alloys, but not the 20 percent nb alloy, following reaction with d20. these results suggest that the oxides formed on the 20 percent nb alloys are a better barrier to d2 ingress only if d2 is not present in a reducing environment (i.e. as d2 gas).