Atomistic study of deformation twinning based on direct observations

2022 Fiscal Year Final Research Report

• Project/Area Number: 20H02421
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 26010:Metallic material properties-related
• Research Institution: The University of Tokyo
• Principal Investigator: Tochigi Eita 東京大学, 生産技術研究所, 准教授 (50709483)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: 変形双晶 / アルミナ / TEM／STEM / その場観察 / 分子動力学計算 / シャッフリング

Outline of Final Research Achievements

Deformation twinning, the formation of a domain with the mirror or two-fold rotation symmetry by applied load, is one of the primary plastic deformation modes of crystalline materials. It is known that deformation twins are formed by slip of twinning dislocations. However, little is known about the detailed behavior of twinning dislocations. In this study, the mechanisms of deformation twinning in alumina ceramics were further examined based on findings obtained by a former research project conducted by the principal investigator. In addition, a new in situ loading experimental system for transmission electron microscopes was developed. This system makes it possible for us to directly observe the nucleation and propagation processes of deformation twins in the atomic resolution.

Free Research Field

材料科学

Academic Significance and Societal Importance of the Research Achievements

本研究により、アルミナセラミックスにおける変形双晶の素過程は、双晶転位の運動に伴いAl原子2個、O原子3個からなる原子集団が互い原子間結合の組み換えを最小限に保ちながら協調的に運動するというものであることが明らかとなった。このような原子集団の協調的な運動は化合物結晶における変形双晶に共通した現象である可能性が高く、変形双晶メカニズムを検討する上で重要な知見と言える。また、新規に開発した透過型電子顕微鏡用その場荷重負荷試験システムは変形双晶の成長過程を原子レベルにて観察できる性能を有しており、今後、変形双晶に関する実験的研究の進展が期待される。