Direct observation of diffusion process of solute atoms by STEM-HAADF observation

Research Project

Project/Area Number	15K14102
Research Category	Grant-in-Aid for Challenging Exploratory Research
Allocation Type	Multi-year Fund
Research Field	Physical properties of metals/Metal-base materials
Research Institution	Tohoku University
Principal Investigator	KAINUMA Ryosuke 東北大学, 工学研究科, 教授 (20202004)
Co-Investigator(Renkei-kenkyūsha)	MURAKAMI YASUKAZU 九州大学, 工学研究院, 教授 (30281992) OMORI TOSHIHIRO 東北大学, 大学院・工学研究科, 准教授 (60451530) NAGASAKO MAKOTO 東北大学, 大学院・工学研究科, 特別教育研究支援者 (30436167)
Project Period (FY)	2015-04-01 – 2017-03-31
Project Status	Completed (Fiscal Year 2016)
Budget Amount *help	¥3,900,000 (Direct Cost: ¥3,000,000、Indirect Cost: ¥900,000) Fiscal Year 2016: ¥1,950,000 (Direct Cost: ¥1,500,000、Indirect Cost: ¥450,000) Fiscal Year 2015: ¥1,950,000 (Direct Cost: ¥1,500,000、Indirect Cost: ¥450,000)
Keywords	電子顕微鏡 / 拡散 / 状態図 / アルミニウム
Outline of Final Research Achievements	For the dilute solid solution alloys A-X (X: Au, Re and W), the direct observation of jumping process of the solute atoms was carried out by STEM-HAADF observation in different several scanning beam conditions. It was confirmed that the frequencies of atomic jump for these alloy systems are higher in the order of Au>Re>W and depend on the scanning rate and the beam intensity. This means that the atomic jump is excited by incident electron beam, not due to the regular diffusion. By precise analysis for the jumping behavior in the Re-doped alloy, it was clarified that the jump is isotropic in direction of every nearest neighbor site. The evaluation of solubility limit of solute element Au was performed by counting all the atomic positions in a fixed flame of the HAADF-STEM image. The obtained result was consistent with that estimated by electric resistant measurement.