Influences of Oxidation State of Nd-Rich Phase on the Coercivity of Nd-Fe-B/Nd Thin Films
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- Matsuura Masashi
- Department of Materials Science, Graduate School of Engineering, Tohoku University
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- Fukada Togo
- Department of Materials Science, Graduate School of Engineering, Tohoku University
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- Goto Ryota
- New Industry Creation Hatchery Center (NICHe), Tohoku University
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- Tezuka Nobuki
- Department of Materials Science, Graduate School of Engineering, Tohoku University
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- Sugimoto Satoshi
- Department of Materials Science, Graduate School of Engineering, Tohoku University New Industry Creation Hatchery Center (NICHe), Tohoku University
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抄録
The Nd-rich phase of Nd-Fe-B sintered magnets, which contains some amount of oxygen, plays an important role for generating coercivity. However, the influence of interfacial microstructure between Nd2Fe14B and Nd-rich phases has not been clear. In this study, Nd2Fe14B/Nd(-O) interface was prepared by thin film technique and the influence of oxidation state of Nd-rich phase on the coercivity was investigated. A Nd-Fe-B layer was deposited by ultra high vacuum (UHV) magnetron sputtering, and the film was oxidized under low vacuum condition (low oxidation state) or Ar atmosphere (high oxidation state). A Nd layer was deposited on the oxidized Nd-Fe-B layer, and the film was annealed at 250–650°C for 60 min. The coercivity of films oxidized in low oxidation state was recovered by annealing at 250–650°C, and an amorphous phase was observed at the interface between Nd2Fe14B and hcp Nd2O3 (+ fcc NdOx) phases in the film annealed at 350°C. On the other hand, the coercivity of films oxidized in high oxidation state was lower than that of films oxidized in low oxidation state, and it decreased more about 20% by annealing at 250–350°C. However, an amorphous phase was not observed at the interface of these films. After annealing above 550°C, the coercivity of films oxidized in both low and high oxidation state recovered drastically to the almost same value of as-deposited film. From the SAD patterns of TEM observation, a metastable C-Nd2O3 phase was present in the Nd-rich phase of these films. In addition, it is known that the wettability of Nd-rich phase improves at temperatures around 550°C. Therefore, it is considered that the increase of coercivity is related to the improvement of fluidity of Nd-rich phase or the existence of C-Nd2O3 phase.
収録刊行物
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- MATERIALS TRANSACTIONS
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MATERIALS TRANSACTIONS 50 (9), 2139-2142, 2009
公益社団法人 日本金属学会
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詳細情報 詳細情報について
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- CRID
- 1390282679226013440
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- NII論文ID
- 10025155483
- 130004454325
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- NII書誌ID
- AA1151294X
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- ISSN
- 13475320
- 13459678
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- NDL書誌ID
- 10334167
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- 本文言語コード
- en
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- データソース種別
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- JaLC
- NDL
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