Fabrication and strength micromechanism of electroplated alloy films having periodic composition-gradient structures

2021 Fiscal Year Final Research Report

• Project/Area Number: 19K05034
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 26030:Composite materials and interfaces-related
• Research Institution: Osaka City University
• Principal Investigator: Kaneko Yoshihisa 大阪市立大学, 大学院工学研究科, 教授 (40283098)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: 電気めっき / 傾斜機能材料 / 合金 / 薄膜 / 強度

Outline of Final Research Achievements

Co-Cu and Ni-Cu alloy films with various gradient compositions were prepared by electroplating and their hardness was measured. In a composition-gradient Co-Cu alloy film, we confirmed the triangular change in Co concentration along the growth direction, and its Vickers hardness was higher than that of the Co-Cu homogeneous alloy film and Co/Cu multilayer film. The hardness of the Ni-Cu alloy film depended strongly on the composition gradient rather than the concentration amplitude, whereas that of the Co-Cu alloy film tended to depend on the concentration amplitude. From the results of hardness tests and X-ray analyses, the strengthening mechanisms based on misfit dislocations and internal stress were assumed to be dominant in the composition-gradient Ni-Cu and Co-Cu alloy films, respectively.

Free Research Field

材料工学

Academic Significance and Societal Importance of the Research Achievements

最近では，バルクナノメタル，長周期積層(LPSO)構造，ハイエントロピー合金など新しい強化原理を掲げた研究が盛んである。本課題の「周期的傾斜構造材料」も新しい強化原理を含んでおり，将来の新分野の種になり得ると期待している。ただし，その強化原理については不明な点が多く残されており，今後の学問的な課題と考えられる。本課題では高濃度勾配の傾斜組成をめっき膜に導入することで硬さが大幅に増加したことから，作業環境が問題となっている硬質クロムめっきを代替できるような構造制御技術になる可能性がある。