Microstructure evolution in D–T neutron irradiated silver

Irradiation of high purity silver with 14 MeV D–T neutrons was carried out at the fusion neutron source facility in Japan Atomic Energy Research Institute. The range of neutron fluence was 6.1×1017 to 1.1×1021 n/m2, which is lower than in earliest D–T neutron irradiations. Thin foil and bulk specimens were irradiated at 288, 423 and 573 K, and observed using transmission electron microscopy. For irradiation at 288 K, the fraction of interstitial clusters in bulk is higher than that in thin foil. In irradiation experiments at 288 and 432 K, the number density of defect clusters is proportional to the neutron fluence to the power of 1.3. In irradiation experiments at 573 K, the defects are mostly stacking fault tetrahedrons (SFTs) and their number density is proportional to the neutron fluence. During isochronal annealing of specimens irradiated at 288 K, disappearance and coalescence of defect clusters were observed, and SFTs were mobile.