熱間加工によるナノコンポジット磁石の異方化

概要

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An anisotropic α-Fe/Nd_2Fe_<14>B nanocomposite magnets were developed using the hot-forming method. The process confirmed that the Nd_2Fe_<14>B crystals in Nd_<10>Fe_<80>Co_5B_5 alloy (α-Fe/Nd_2Fe_<14>B type) exhibited an orientation along the stress direction during a hot-forming process over 1000℃. The mechanism thought to induce such an anisotropy in α-Fe/NdaFeuB type is primarily attributed to a grain boundary rotation under uniaxial stress at high temperatures. The hot-formed specimens that displayed anisotropy, however, showed a noticeable grain growth with the size of up to approximately 1 fj.m and did not exhibit sufficient hard magnetic properties. The effect of an additive element on the magnetic properties of a hot-formed α-Fe/Nd_2Fe_<14>B type magnet was also investigated. A Cu addition to the α-Fe/Nd_2Fe_<14>B type magnet proved to induce the anisotropic orientation at lower temperature, which is in contrast with the results of nonadditive specimens. The Cu-added specimens have a crystal size of 50 to 100 nm. These results show that the magnetic properties of nanocomposite magnets can be expected to be improved by controlling their microstructure.
社団法人日本磁気学会の論文
2004-12-01