Developments of the three dimensional nanoscale analysis for acceleration effects on the interface corrosion of neutron irradiated steels

2021 Fiscal Year Final Research Report

• Project/Area Number: 19K05323
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 31010:Nuclear engineering-related
• Research Institution: Tohoku University
• Principal Investigator: Yoshida Kenta 東北大学, 金属材料研究所, 准教授 (10581118)
• Co-Investigator(Kenkyū-buntansha): 嶋田 雄介 東北大学, 金属材料研究所, 助教 (20756572)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: 電子顕微鏡 / 照射欠陥 / 腐食 / 転位

Outline of Final Research Achievements

In this study, we developed a "3D nanoanalysis for corrosion interface", which consists of a reaction tank that can introduce electrochemically controlled corrosion to activated nuclear materials and analytical instruments that can visualize and quantify the strain and chemical composition of interface corrosion in nanometer scale.
The 3D nanoanalysis method was applied to neutron-irradiated materials such as F82H, ODS, low-activated steels, then the sizes of dislocation loops before and after corrosion tests were quantitatively analyzed in three dimensions with a resolution of 1 nm. The behavior of solute atomic clusters and nanovoids during corrosion was quantitatively analyzed in a three-dimensional space.

Free Research Field

ナノ材料化学

Academic Significance and Societal Importance of the Research Achievements

我々が最近独自開発してきたウィークビーム走査型透過電子顕微鏡（WB-STEM）法の特徴を最大限活かし、「腐食界面３次元ナノ分析法」を開発することで、原子炉の安全に直結する構造材料の未だ理解されていない腐食機構を解明することを目的とした。具体的には、カソード分極試験を行い腐食生成物（γ-FeOOH, マグネタイト）の量や分布を３次元イオンビーム加工（3D-SEM-FIB）を用いた３次元ナノ分析によって評価した。この段階で数十ナノ～数マイクロの空隙と腐食生成物など、材料内部への腐食界面の侵食可視化し、本研究課題の目的であるナノスケールの照射欠陥と粒界腐食の複合的影響の確認は達成された。