In situ transmission electron microscopy with dual ion beam irradiation and implantation.

To study the helium effects and their interactions with displacement damage in irradiated materials, an in situ dual-ion beam irradiation capability with transmission electron microscopy was recently established at the IVEM-Tandem Facility at Argonne National Laboratory. Pure nickel was irradiated in situ individually with 1 MeV Kr ions for displacement damage study, 16 keV He ions for helium implantation, and simultaneously with 1 MeV Kr ions and 16 keV He ions at the rate of 1 at.% He/dpa to study the interaction of helium and displacement damage at 500 °C. Helium bubbles were formed and segregated within dislocation loops during the He implantation experiment and no bubbles were observed outside the loops. The loop size increased with increasing helium concentration. In contrast, helium bubbles were formed uniformly in the matrix when nickel was irradiated simultaneously with 1 MeV Kr ions and 16 keV He ions. It is suggested that the uniformly-distributed defect clusters formed under 1 MeV Kr ion irradiation serve as trapping sites of helium atoms resulting in homogeneous nucleation of helium bubbles under the dual-ion beam irradiation in nickel. • In situ TEM study of interaction of helium implantation and displacement damage under dual-ion beams. • Heterogenous distribution of helium bubbles was observed inside dislocation loops under 16 keV helium ion implantation. • Distinctly different distributions of helium bubbles and dislocation loops were observed by TEM in pure nickel under in situ single and dual-beam irradiations. [ABSTRACT FROM AUTHOR]