Elucidation of mechanism of segregation of solute atom to dislocations

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K04623
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 26010:Metallic material properties-related
• Research Institution: Tohoku University
• Principal Investigator: Inoue Koji 東北大学, 金属材料研究所, 准教授 (50344718)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: アトムプローブ

Outline of Final Research Achievements

Three-dimensional distribution of solute atoms in edge and screw dislocations was observed by atom probe tomography. A new sample preparation method was developed to efficiently observe the segregation of solute atoms to dislocations. The measurement samples were fabricated using a focused ion beam (FIB) apparatus, but it is difficult to observe dislocations using the scanning electron microscope equipped with the FIB. Therefore, a needle sample was prepared using the FIB and then observed by transmission electron microscope to confirm the position of the dislocations in the needle sample, and additional FIB processing was performed again. A sample containing dislocations at the needle tip was prepared, and the three-dimensional elemental distribution of solute atoms at the dislocation was obtained. Since this method can be applied not only to dislocations but also to various kinds of crystal lattice defects, the segregation around voids was also clarified.

Free Research Field

材料分析

Academic Significance and Societal Importance of the Research Achievements

構造材料でもっとも重要な鉄鋼材料において、Cの分布は機械的特性に大きな影響を与えるため、その詳細を理解することは、今後の材料開発にとって重要である。Cは軽元素であるため従来の手法では検出しにくく、今回、原子１個１個を３次元実空間で見ることのできる３次元アトムプローブを用い、さらに試料作製方法を工夫することで、転位などの特定部位のCの分布について明らかにした。今回開発した手法は転位に限らず、さまざまな格子欠陥に適用できる。さらに、鉄鋼材料以外の材料への適用も可能である。そのため、一例としてタングステン中のボイド周囲の核変換元素の偏析についても適応し、この手法の有効性を示した。