title: TEM investigation on the microstructural evolution of Hastelloy N induced by Ar⁺ ion irradiation.
abstract: Hastelloy N alloy has been selected as the primary structure material for molten salt reactor. In this article, Hastelloy N alloy samples were irradiated to different doses at room temperature using 300 keV Ar(+) ions. The microstructural evolution was investigated by transmission electron microscopy (TEM) and energy-dispersive spectroscopy (EDS). Black dot defects emerged in sample irradiated at low dose (0.4 displacement per atom (dpa)), and they grew up with irradiation doses (0.4-2 dpa). A high density of small dislocation loops (nano meters in size) were observed in the sample irradiated to 4 dpa. When the ion dose increased to 12 dpa, complicated structures with defects (including dislocation lines, larger loops and smaller black dots) were observed. Dislocation networks were detected from high-angle annular dark field (HAADF) images. Larger dislocation loops (size: 30-80 nm) were visible in the sample irradiated to 40 dpa. Irradiation with dose of 120 dpa led to the formation of face-centered cubic nanocrystallites with preferred orientations.
authors.affiliation: University of Chinese Academy of Sciences, Beijing, 100049, China; Department of Nuclear Materials Science and Engineering, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai, 201800, China.
authors.forename: Min
authors.initials: M
authors.lastname: Liu
authors.forename: Yanling
authors.initials: Y
authors.lastname: Lu
authors.forename: Renduo
authors.initials: R
authors.lastname: Liu
authors.forename: Xingtai
authors.initials: X
authors.lastname: Zhou
keywords: Hastelloy N alloy; TEM; ion irradiation; microstructural evolution; nanocrystallites induced by irradiation