Realization of reversible plasticity in metals by mechanical control of self-organized dislocation structure

2023 Fiscal Year Final Research Report

• Project/Area Number: 22K18754
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 18:Mechanics of materials, production engineering, design engineering, and related fields
• Research Institution: Kyoto University
• Principal Investigator: Sumigawa Takashi 京都大学, エネルギー科学研究科, 教授 (80403989)
• Project Period (FY): 2022-06-30 – 2024-03-31
• Keywords: 自己組織化 / 転位構造 / 金属 / 可逆塑性 / 繰り返し負荷

Outline of Final Research Achievements

The purpose of this study was to create a material that undergoes reversible plastic deformation by focusing on the peculiar self-organized dislocation structure formed inside micro-sized single crystal metals under cyclic loading. Nickel single crystals with a square cross section of two micrometers on a side were subjected to tension-compression cyclic loading at stress amplitudes lower than the fatigue crack initiation limit of bulk Ni. The specimen oriented to a particular crystallographic orientation showed elastic deformation in the early stages, but exhibited large plastic strain from the middle of the testing. Internal observation of the specimen after the experiment revealed that a structure similar to the ladder-like dislocation one found in the bulk was formed throughout the gauge section of the specimen, and analysis of reaction-diffusion system revealed that surface effects produced the peculiar dislocation structure.

Free Research Field

材料力学、材料強度学

Academic Significance and Societal Importance of the Research Achievements

本研究では、ミクロンサイズの材料では、繰り返し負荷によって形成される転位の自己組織化転位構造に対して表面の影響が材料全体に及ぼされることを実験および解析によって明らかにし、結晶方位や材料寸法を調節することで目的とする転位構造を材料全体に発現できる可能性を示した。本成果は、転位の自己組織化構造の制御によって材料に特有の機械特性を生み出すという新しい学術分野を開拓するものであることに加え、将来的にはこれを利用した高機能構造物の創出の可能性も見込まれることから、学術界のみならず産業界や社会へ大きく貢献するものである。