Research of new FCC structure materials by the stacking fault energy control

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K05125
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 26040:Structural materials and functional materials-related
• Research Institution: Hokkaido University
• Principal Investigator: Hashimoto Naoyuki 北海道大学, 工学研究院, 教授 (50443974)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: 照射損傷 / 微細組織 / 低放射化 / 構造材料

Outline of Final Research Achievements

In recent years, high entropy alloys (HEAs) have attracted attention as a high radiation resistance material at high temperatures. In this study, we investigated the effects of Mn and Ni composition on the change of mechanical property and microstructure development in FeCrNiMn-based alloys under irradiation.
The results of the present study indicate that the stacking fault energy of FeCrNiMn-based alloys seemed to be increased with increasing Mn and Ni concentration. Furthermore, the ion-irradiation to the alloys resulted in the formation of plane defects such as stacking fault tetrahedra and frank loops. The number density and the average size of these defects appeared to have a strong relationship with stacking fault energy of each alloy. From these results, it is suggested that FeCrNiMn-based alloys could be improved to a higher irradiation resistance alloy with an appropriate stacking fault energy by controlling Mn and Ni concentration.

Free Research Field

原子力材料、構造材料

Academic Significance and Societal Importance of the Research Achievements

既存軽水炉構造材料の開発研究は、高信頼性と高安全性を有するオーステナイトステンレス鋼や低合金鋼などの鉄鋼材料を中心に行われてきたが、近年になって、特異な材料特性を有するハイエントロピー合金を原子炉構造材料へ応用するための基礎研究が活発化してきた。照射下におけるFCC型構造材料中には、フランク型転位ループや積層欠陥四面体といった積層欠陥型の照射欠陥が形成することで、材料の照射硬化や照射脆化を引き起こす。本研究では、MnおよびNiの濃度を変えることで積層欠陥エネルギーを制御し、耐照射特性を向上させることに成功した。これにより、次世代の新規炉構造材料開発の道筋の一つを提案することができた。