Development of nanocrystalline /amorphous dual phase alloy with high strength and high ductility using brushing-electrodeposition technique

2018 Fiscal Year Final Research Report

• Project/Area Number: 16K06776
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Structural/Functional materials
• Research Institution: University of Hyogo
• Principal Investigator: Adachi Hiroki 兵庫県立大学, 工学研究科, 准教授 (00335192)
• Research Collaborator: YAMASAKI tohru
• Project Period (FY): 2016-04-01 – 2019-03-31
• Keywords: ナノ結晶アモルファス二相合金 / 延性 / 経時変化 / 合金元素添加 / 電解析出法

Outline of Final Research Achievements

The nanocrystalline/ amorphous dual phase Ni-W alloys produced by brushing electrodeposition exhibit extremely high strength of over 2GPa and have sufficient plastic deformability. However, by long-term aging at a temperature above room temperature, the plastic elongation gradually decreased. In order to suppress this change, in this study, the third element addition was tired. First, addition of nitrogen and boron, which are interstitial atoms for Ni alloys, were tried. Though, since the amounts of the solute atoms were small, the change with time could not be suppressed. So, addition of cobalt and molybdenum, which are substitutional atoms for Ni alloys, were tried. By brushing technique, Ni-W-Co and Ni-W-Mo with few electrodeposition defects can be prepared and the change of elongation with time can be suppressed.

Free Research Field

材料組織学

Academic Significance and Societal Importance of the Research Achievements

Ni-W合金は引張強度2GPa以上の強度を示すが、ほとんど延性を示さない脆性材料であった。しかし、ブラッシング電析法を用いることにより電析欠陥をほとんど示さないナノ結晶/アモルファス二相Ni-W合金は最大8%程度の塑性伸びを有する。しかしながら、室温以上の温度における長時間保持により塑性伸びが徐々に減少する経時変化を示す。本研究では、これをアモルファス相の熱的安定度が低いため室温保持により自由体積が低下し、ナノ結晶内において変形を担う転位が生じにくくなるためであることを明らかにし、それを第三元素添加により抑制できることを明らかにした。