title: Weak-beam scanning transmission electron microscopy for quantitative dislocation density measurement in steels.
abstract: To evaluate dislocations induced by neutron irradiation, we developed a weak-beam scanning transmission electron microscopy (WB-STEM) system by installing a novel beam selector, an annular detector, a high-speed CCD camera and an imaging filter in the camera chamber of a spherical aberration-corrected transmission electron microscope. The capabilities of the WB-STEM with respect to wide-view imaging, real-time diffraction monitoring and multi-contrast imaging are demonstrated using typical reactor pressure vessel steel that had been used in an European nuclear reactor for 30 years as a surveillance test piece with a fluence of 1.09 × 1020 neutrons cm-2. The quantitatively measured size distribution (average loop size = 3.6 ± 2.1 nm), number density of the dislocation loops (3.6 × 1022 m-3) and dislocation density (7.8 × 1013 m m-3) were carefully compared with the values obtained via conventional weak-beam transmission electron microscopy studies. In addition, cluster analysis using atom probe tomography (APT) further demonstrated the potential of the WB-STEM for correlative electron tomography/APT experiments.
authors.affiliation: International Research Center for Nuclear Materials Science, Institute for Materials Research, Tohoku University, Oarai, Ibaraki 311-1313, Japan.
authors.forename: Kenta
authors.initials: K
authors.lastname: Yoshida
authors.affiliation: International Research Center for Nuclear Materials Science, Institute for Materials Research, Tohoku University, Oarai, Ibaraki 311-1313, Japan.
authors.forename: Masaki
authors.initials: M
authors.lastname: Shimodaira
authors.affiliation: International Research Center for Nuclear Materials Science, Institute for Materials Research, Tohoku University, Oarai, Ibaraki 311-1313, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Toyama
authors.affiliation: International Research Center for Nuclear Materials Science, Institute for Materials Research, Tohoku University, Oarai, Ibaraki 311-1313, Japan.
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Shimizu
authors.affiliation: International Research Center for Nuclear Materials Science, Institute for Materials Research, Tohoku University, Oarai, Ibaraki 311-1313, Japan.
authors.forename: Koji
authors.initials: K
authors.lastname: Inoue
authors.affiliation: Research Reactor Institute, Kyoto University, Kumatori-cho, Sennan-gun, Osaka 590-0494, Japan.
authors.forename: Toshimasa
authors.initials: T
authors.lastname: Yoshiie
authors.affiliation: SCK-CEN, Nuclear Materials Science Institute, Boeretang 200, 2400 Mol, Belgium.
authors.forename: Konstantinovic J
authors.initials: KJ
authors.lastname: Milan
authors.affiliation: Tractebel Engie, Avenue Ariane, 1200 Brussels, Belgium.
authors.forename: Robert
authors.initials: R
authors.lastname: Gerard
authors.affiliation: International Research Center for Nuclear Materials Science, Institute for Materials Research, Tohoku University, Oarai, Ibaraki 311-1313, Japan.
authors.forename: Yasuyoshi
authors.initials: Y
authors.lastname: Nagai
keywords: STEM; diffraction contrast; dislocation; irradiation damage; weak-beam