Magnetic Properties of α-Fe-Nd2Fe14B Exchange Spring Magnets Synthesized by Mechanical Alloying (特集 アモルファス-ナノ・グラニュラ-機能材料 1) Magnetic Properties of α-Fe-Nd_2Fe_<14>B Exchange Spring Magnets Synthesized by Mechanical Alloying
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The possibility of producing isotropic permanent magnets with enhanced energy product has drawn lot of attention recently. The synthesis of two phase (hard and soft) nanocrystalline exchange coupled magnets by many research groups using different techniques and the various combination of two phases is an indication to the level of research interest in this area. The nitrogenated or carburized rare earth compounds with 2:17 or 1:12 structure as the hard phase was the focal point of many groups. However, the choice of Nd<SUB>2</SUB>Fe<SUB>14</SUB>B as the hard phase with the attractive advantages of single stage heat treatment, no drawbacks of incomplete nitrogenation or carburization and the possibility of higher sintering temperature has tilted the scale in its favor. The present article reports on the results of the synthesis of exchange spring magnets of Nd<SUB>2</SUB>Fe<SUB>14</SUB>B and α-Fe and their magnetic properties by mechanically alloying the powder mixture of Nd<SUB>2</SUB>Fe<SUB>14</SUB>B and iron. The magnets exhibit a spring back greater than 80% and a maximum energy product of 45 kJ/m<SUP>3</SUP>. The observed large spring back is an indication of the good coupling between the hard and the soft phases. The low energy product is attributed to the low coercivity of the starting Nd<SUB>2</SUB>Fe<SUB>14</SUB>B powder and requires further improvement.
- J. Jpn. Soc. Powder Powder Metallurgy
J. Jpn. Soc. Powder Powder Metallurgy 43(5), 634-639, 1996-05-15
Japan Society of Powder and Powder Metallurgy