Characterization and stability studies of titanium beryllides

Beryllides appear as potential candidates to replace Be in future fusion power plants due to their improved properties. However, while the fabrication and properties of beryllium are well established a lack of knowledge still exists for beryllides. In this work, we present a detailed characterization of titanium beryllides, provided by JAERI in the frame of the IEA agreement, using a large number of techniques. Compositions of Be–5 at% Ti and Be–7 at% Ti were used to produce the samples. High resolution X-ray diffraction clearly shows the formation of Be10Ti phase for the Be–7 at% Ti composition. For the Be–5 at% Ti, the major phase is Be12Ti with traces of a Be-rich phase. In both cases, no evidence was found for the presence of pure Be phase in the samples. Ti elemental maps obtained with a scanning nuclear microprobe reveals the presence of regions containing large amounts of Cr, Mn, Fe, Ni, Cu and in some cases U. These impurities are common in Be and this behaviour suggests that a segregation process occurs during the beryllide formation. Moreover, the RBS spectra also show the presence of oxygen in this region while it seems to be depleted from the beryllide bulk. The oxidation seems to occur preferentially along the beryllide boundaries and Ti depleted region.