Evolution of beryllium microstructure under high-dose neutron irradiation

Beryllium is an advantageous material from the point of its usage in some components of perspective fusion reactors, such as reactor wall, divertor and blanket. The character of the microstructure change under neutron irradiation of beryllium is a determining factor in understanding of the processes resulting in the degradation of physical–mechanical properties of the material. The performed examinations of the TE-56 beryllium grade irradiated in the SM-reactor at 70–120 °C up to fluences of 2.5×1022 to 5.7×1022 cm−2 (E>0.1 MeV) and TE-400 beryllium grade irradiated in the BOR-60 reactor at 400 °C up to a fluence of 1.6×1023 cm−2 (E>0.1 MeV) demonstrated that low-temperature irradiation resulted in the generation of dislocation loops and high-temperature irradiation resulted in the generation of plane hexahedral voids in a basal plane. The effect of short-term high-temperature annealing on the microstructure after low-temperature irradiation is studied also. One hour anneal at 300–1200 °C gives rise to loops and results in their evolution in dislocation network as well as generation and growing of the gas bubbles.