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Formation of Exclusive Al2O3 Scale on Nb and Nb-Rich Alloys by Two-Step Oxygen-Aluminum Diffusion Process

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タイトル: Formation of Exclusive Al2O3 Scale on Nb and Nb-Rich Alloys by Two-Step Oxygen-Aluminum Diffusion Process
著者: Hayashi, Shigenari 著作を一覧する
Takagi, Shinsuke 著作を一覧する
Yamagata, Ryutaro 著作を一覧する
Narita, Toshio 著作を一覧する
Ukai, Shigeharu 著作を一覧する
キーワード: Nb based alloy
Oxidation resistance
Exclusive Al2O3 scale formation
Oxygen-aluminum diffusion treatment
発行日: 2012年10月
出版者: Springer-Verlag
誌名: Oxidation of Metals
巻: 78
号: 3-4
開始ページ: 167
終了ページ: 178
出版社 DOI: 10.1007/s11085-012-9298-2
抄録: External Al2O3 scale formation behavior by a diffusion aluminizing process on Nb and Nb-X (X = Mo, Re, and Ta) alloys with different oxygen solubilities was investigated. The oxygen content in Nb and Nb-X alloys was controlled by oxygen diffusion treatment at 1,100 A degrees C using Nb/NbO mixture. Nb-aluminide, NbAl3 and Nb2Al, layers were developed on the low-oxygen Nb substrate by an aluminum diffusion treatment using Al/Al2O3/NH4Cl mixture at 1,100 A degrees C; whereas an adhesive Al2O3 scale developed on the Nb substrate with higher oxygen content. The alloy oxygen content decreased by an addition of Ta, Mo and Re, in this order, and the decrease in alloy oxygen content resulted in the transition of Al2O3 formation from external scale to internal precipitates. This transition was not observed when low Al activity powder mixture, Ni50Al/Al2O3/NH4Cl, was used for Al diffusion process, and only external Al2O3 scale was developed on all samples. In the present study, the effects of oxygen solubility limit, oxygen content, and the activity of Al in diffusion process on the formation of Al2O3 scale will be discussed.
Rights: The final publication is available at
資料タイプ: article (author version)
出現コレクション:雑誌発表論文等 (Peer-reviewed Journal Articles, etc)

提供者: 林 重成


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