Degradation processes and helium swelling in beryllium oxide

Abstract

The work is devoted to the investigation of the processes of defect formation and helium swelling of the surface layer of BeO ceramics upon irradiation with helium ions with fluences of 1 × 1017–5 × 1017 ion/cm2. The choice of the type of ions for irradiation and irradiation fluence is due to the possibility of modeling the processes of helium accumulation in the structure of ceramics used as structural materials of nuclear reactors. The study found that at irradiation doses of 3 × 1017–5 × 1017 ion/cm2, the formation of an impurity cubic phase of beryllium oxide with a spatial syngony Fm-3m (225) is observed, the concentration of which increases with fluence. According to SEM images and AFM data, the formation of spherical inclusions - hillocks, whose density increases with fluence, is observed on the surface of irradiated samples. The formation of spherical inclusions is due to the accumulation of helium in the structure of the surface layer with subsequent agglomeration and the formation of helium bubbles near the grain boundaries.