Dy拡散処理におけるNdFeB系焼結磁石の組織改善効果 Effects of Microstructural Improvements on Dy-diffusion Processed NdFeB Sintered Magnets

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Dy-diffusion process is one of effective methods to improve the coercivity of NdFeB sintered magnets with a small amount of Dy usage. In order to achieve further improvements of coercivity, we investigated microstructural factors such as grain size and impurity of NdFeB sintered magnets after Dy-diffusion treatment. One of our results indicates that oxygen, as existing impurity in NdFeB magnets, reacts with the diffused Dy to generate Nd-Dy oxide which mainly remains at triple junctions of NdFeB grains. As the oxidization of Dy could not work to improve coercivity, reducing the oxygen content is effective to enhance the Dy-diffusion effect. On the other hand, we tried another technique to protect from oxidization of Dy, in which rare-earth fluorides were doped into NdFeB sintered body. We found that the doped fluoride could trap oxygen such as the formation of NdOF. After that, Dy could smoothly come into grain boundaries because of non-reaction with oxygen. Then, coercivity of magnets showed to be remarkable improvement.

Dy-diffusion process is one of effective methods to improve the coercivity of NdFeB sintered magnets with a small amount of Dy usage. In order to achieve further improvements of coercivity, we investigated microstructural factors such as grain size and impurity of NdFeB sintered magnets after Dy-diffusion treatment. One of our results indicates that oxygen, as existing impurity in NdFeB magnets, reacts with the diffused Dy to generate Nd-Dy oxide which mainly remains at triple junctions of NdFeB grains. As the oxidization of Dy could not work to improve coercivity, reducing the oxygen content is effective to enhance the Dy-diffusion effect. On the other hand, we tried another technique to protect from oxidization of Dy, in which rare-earth fluorides were doped into NdFeB sintered body. We found that the doped fluoride could trap oxygen such as the formation of NdOF. After that, Dy could smoothly come into grain boundaries because of non-reaction with oxygen. Then, coercivity of magnets showed to be remarkable improvement.

収録刊行物

  • 粉体および粉末冶金

    粉体および粉末冶金 59(3), 156-160, 2012-03-15

    一般社団法人 粉体粉末冶金協会

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各種コード

  • NII論文ID(NAID)
    10030479991
  • NII書誌ID(NCID)
    AN00222724
  • 本文言語コード
    JPN
  • 資料種別
    ART
  • ISSN
    05328799
  • NDL 記事登録ID
    023618081
  • NDL 請求記号
    Z17-274
  • データ提供元
    CJP書誌  NDL  J-STAGE 
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