X-ray study of surface layers of air-annealed Be12Ti and Be12V samples using synchrotron radiation
Highlights
► Surface layers of air-annealed Be12Ti and Be12V samples were investigated. ► X-ray diffraction analysis using synchrotron radiation allowed the study of near-surface regions with the depths of a few microns. ► Presence of beryllium oxide BeO was found in all investigated surface layers of Be12Ti and Be12V samples. ► Volatilization of vanadium oxide V2O5 was observed from the surface of Be12V sample after annealing at 800 °C.
Introduction
Titanium beryllide Be12Ti and vanadium beryllide Be12V are considered to be advanced materials for the use as neutron multipliers in the solid breeding blanket [1], [2], [3]. However as the gas release kinetics and the compatibility with structural materials strongly depend on the oxidation behavior, the proper investigation of their resistance to oxidation at elevated temperatures is needed.
Gas release characteristics of neutron multiplier are in a strong dependency on the presence of oxide layer on the surface of beryllium-based materials. It is known that the diffusivity and solubility of hydrogen isotopes (e.g., tritium) can be influenced by the presence of different oxides in near-to-surface layers of beryllium-containing materials [4], [5], [6].
In this article we report on phase composition of six layers deposited at the depths up to 20 μm from the surfaces of Be12Ti and Be12V samples investigated by means of synchrotron radiation using X-ray diffraction technique.
Section snippets
Materials
This work was performed using Be12Ti and Be12V intermetallic compounds delivered by Company Brush Wellman, Inc., USA. Both types of beryllide specimens were produced using powder metallurgical methods and have nearly equal densities of about 2.40 g/cm3.
Investigations of initial and air-annealed Be12Ti and Be12V samples by scanning electron microscope (SEM)
SEM observations of the surfaces of beryllide specimens in as-received state show the separate grains on the surfaces of Be12Ti and Be12V samples, accordingly (Fig. 1 and Fig. 2).
After investigations of the surfaces of beryllide samples in the
Results and discussion
Fig. 7, Fig. 8 show X-ray diffraction patterns corresponding to annealed Be12Ti and Be12V samples. One should emphasize that 10.2 keV X-ray wavelength in vacuum is 1.215534 A. Therefore, peak positions of beryllides and appropriate oxides were recalculated using Diffrac Plus evaluation software taking into account the wavelength corresponding to incident synchrotron radiation. The X-ray penetration depth decreased from the lowermost down to the uppermost curves (attenuation lengths decrease,
Conclusions
The study of the surface layers of air-annealed Be12Ti and Be12V samples showed that beryllium oxide is present in the whole volume of materials’ near-to-surface region. In the case of oxidation of Be12Ti specimen, only one peak identified as TiO2 (3 1 0) was found in deeper layers located closer to material bulk. Oxidation of Be12V specimen led to additional formation of highly volatile V2O5 which may cause the appearance of undesirable gas species in the breeding blanket. For both, Be12Ti and Be
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Cited by (1)
Synthesis and characteristics of ternary Be–Ti–V beryllide pebbles as advanced neutron multipliers
2016, Fusion Engineering and DesignCitation Excerpt :In contrast, the Zr in Be13Zr is so highly reactive that it is difficult to handle without a globe box controlled by an inert gas. Furthermore, vanadium beryllide has some disadvantages such as high cost and an insufficiency of data on granulated pebbles, although a study on the fabrication of Be12V blocks with the powder metallurgical method has been reported [6]. Therefore, to solve issues pertaining to binary beryllides, granulation of Be12Ti1−xVx ternary beryllides with different amounts of V was conducted in the present study.
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Present address: Insitut für Angewandte Physik und Zentrum für Mikrostrukturforschung, Jungiusstrasse 11, D-20355 Hamburg, Germany.