Nanoscale characterization of beryllide materials

The most recent version of the Helium Cooled Pebble Bed (HCPB) foreseen for the European DEMO blanket considers solid blocks of titanium beryllide as neutron multiplicator material. The advantage of beryllide materials over pure beryllium is their higher operating temperature, higher corrosion resistance, lower swelling, and retention of tritium under neutron irradiation. Understanding the micro- and nanostructure especially after neutron irradiation is of crucial importance for the qualification process of the material.
The focus of this work will lie on the transmission electron microscopy (TEM) characterization of a titanium beryllide/beryllium composite material irradiated at two different temperatures during the HIDOBE neutron irradiation campaign. In particular, the structure and chemistry of the nanosized cavities in the pure beryllium region and the beryllide region was analyzed and is compared to each other. Apart from the cavities, structural defects were observed in the beryllide region that are not known from irradiated pure beryllium.
The presented results can be used for understanding and quantifying for example tritium retention in beryllide materials and to further optimize the material synthesis and the breeding blanked design in general.