Kink control and its bulk development in various Mg alloys with millefeuille structure

2022 Fiscal Year Final Research Report

• Project Area: Materials science on mille-feullie structure -Developement of next-generation structural materials guided by a new strengthen principle-
• Project/Area Number: 18H05477
• Research Category: Grant-in-Aid for Scientific Research on Innovative Areas (Research in a proposed research area)
• Allocation Type: Single-year Grants
• Review Section: Science and Engineering
• Research Institution: National Institute for Materials Science
• Principal Investigator: Somekawa Hidetoshi 国立研究開発法人物質・材料研究機構, 構造材料研究拠点, グループリーダー (50391222)
• Co-Investigator(Kenkyū-buntansha): 戸高 義一 豊橋技術科学大学, 工学(系)研究科(研究院), 教授 (50345956)
• Project Period (FY): 2018-06-29 – 2023-03-31
• Keywords: キンク / マグネシウム / 材料プロセス / 強ひずみ加工 / 力学特性 / 微細組織 / ミルフィーユ構造

Outline of Final Research Achievements

It is well-recognized that kink bands, which have the strengthening effect, are induced to the long-periodic stacking order (LPSO) phase by wrought processing. In this study, we had two major purposes for clarifying i) effective process to induce kink bands and ii) suitable microstructural feature relating to kink bands, which highly contributes to strengthening. We successfully produced many types of bulks that can identify between the influential microstructural factors and the kink strengthening effect, with controlling kink structure and morphology via thermomechanical processes. We found out that a high dispersion of kink bands consisting of narrow-spaces and fine-sizes are effective to attain high kink strengthening effect. In addition, we demonstrated that control of shear strain is important to induce such kink morphologies and structures to the LPSO phase.

Free Research Field

材料工学

Academic Significance and Societal Importance of the Research Achievements

「加工-組織-特性」の普遍化は、従来冶金学における永遠の課題と言われている。プロセス条件、微細組織変化および力学応答を独立した個別解として扱わず、キンク関連因子として捉えることで、『せん断ひずみ-キンク数密度-局所硬度』によって整理、表記できることを明示した。本知見は、当該学術分野に風穴をあける極めて重要な成果といえる。