title: Morphological and chemical analysis of bainite in Cu-17Al-11Mn (at.%) alloys by using orthogonal FIB-SEM and double-EDS STEM.
abstract: In this study, new microscopy techniques were developed for understanding the mechanism for the bainitic transformation in a Cu-17Al-11Mn (at%) alloy. An orthogonally arranged focused ion beam and a scanning electron microscope were employed to observe three-dimensional (3D) morphology of the bainite phase, in addition to compositional analysis by using a scanning transmission electron microscope equipped with a double-detector energy-dispersive X-ray spectrometer system. The 3D morphology of these samples was observed at different aging times and aging temperatures; the results obtained indicated that with increasing aging time and/or aging temperature, the bainite phase at the initial stage of formation exhibits a plate-like shape, which changes to a lenticular form. A habit plane was uniquely determined as ∼{9 3 2} by the combination of 3D image reconstruction and an electron back-scattered diffraction technique. The compositional analysis revealed the spatial distribution of the compositional variation between the bainite and matrix phases in the initial stages of the transformation. In the bainite phase, the Cu concentration was higher, while the concentrations of Al and Mn were lower than those in the surrounding matrix, indicative of the diffusion of the constituent elements with the growth of the bainite phase.
authors.affiliation: Department of Applied Science for Electronics and Materials, Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, Kasuga, Fukuoka 816-8580, Japan motomura.shunichi@nims.go.jp.
authors.forename: Shunichi
authors.initials: S
authors.lastname: Motomura
authors.affiliation: Surface Physics and Structure Unit, Advanced Key Technologies Division, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan Department of Engineering Science for Electronics and Materials, Faculty of Engineering Science, Kyushu University, Kasuga, Fukuoka 816-8580, Japan.
authors.forename: Toru
authors.initials: T
authors.lastname: Hara
authors.affiliation: Department of Materials Science, Graduate School of Engineering, Tohoku University, Aoba-yama 6-6-02, Sendai 980-8579, Japan.
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Omori
authors.affiliation: Department of Materials Science, Graduate School of Engineering, Tohoku University, Aoba-yama 6-6-02, Sendai 980-8579, Japan.
authors.forename: Ryosuke
authors.initials: R
authors.lastname: Kainuma
authors.affiliation: Department of Engineering Science for Electronics and Materials, Faculty of Engineering Science, Kyushu University, Kasuga, Fukuoka 816-8580, Japan.
authors.forename: Minoru
authors.initials: M
authors.lastname: Nishida
keywords: 3D reconstruction; FIB-SEM dual-beam; bainitic transformation; electron back-scattered diffraction; energy dispersive X-ray spectrometry; serial-sectioning