Control of grain boundary segregation in ferrous alloys using interaction between solute elements

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K14433
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 26050:Material processing and microstructure control-related
• Research Institution: Tohoku University
• Principal Investigator: Zhang Yongjie 東北大学, 金属材料研究所, 助教 (40793740)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: 粒界偏析 / 鉄鋼材料 / 合金元素 / 溶質元素間相互作用 / アトムプローブ

Outline of Final Research Achievements

Solute segregation at grain boundaries in polycrystalline metals has strong effects on various material properties. In this study, the segregation behaviors of C, P, N and Sn in bcc-Fe were investigated. By considering the influence of grain boundary character, quantitative evaluation using three-dimensional atom probe was performed to clarify the influence of interaction between solute elements on grain boundary segregation. In the Fe-P binary alloy, the segregation amount of P increased with larger boundary misorientation. As for the high-angle grain boundaries in the other Fe-X binary alloys, the segregation amounts did not increase linearly with the addition amounts, indicating the repulsive interaction between each element. Furthermore, in the Fe-P-C and Fe-Sn-C ternary alloys, the segregation of P and Sn was suppressed by C addition, which revealed the role played by their repulsive interaction with C.

Free Research Field

金属材料の組織制御

Academic Significance and Societal Importance of the Research Achievements

本研究で明らかとなったBCC鉄における溶質偏析におよぼす粒界性格の影響により、過去の研究で報告された結果の位置づけが明確になると考えられる。また、溶質間相互作用の寄与に関する知見に基づき、鉄合金における各種溶質の共偏析・競合偏析現象を制御することが可能になる。さらに、それらの現象の本質的理解により、カーボンニュートラルの達成に向けて、溶質偏析の制御に基づいた実用鋼の機械的特性向上が期待される。