Microstructure change and swelling of helium irradiated beryllium

Abstract Beryllium, as an outstanding nuclear metal, will be exposed to high-dose irradiation of high-energy neutrons during services in reactor, which will produce a large number of helium and significant irradiation damage resulting in extreme performance degradation. In this paper, microstructure change and swelling of helium irradiated beryllium have been investigated using transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM). Inside the grain, some impurity particles were observed and be revealed to be Fe/Al/Mn/Cr-rich beryllide phase with fcc structure. Beryllium metal was irradiated with 30 keV helium ion to a dose of 1 × 10 17 He + /cm 2 at room temperature. A high density of dislocation loop was induced in the sample after the irradiation. The types of loops in beryllium were summarized. Meanwhile, helium bubbles with average size of 2.7 nm were observed. Helium irradiation induced swelling and temperature effect were discussed.