Sm_2Fe_<17>N_3新磁石の発見 The Discovery of Sm_2Fe_<17>N_3 Permanent Magnet Material
We discovered a new compound Sm<SUB>2</SUB>Fe<SUB>17</SUB>N<SUB>3</SUB> in 1987 through the investigation of the structural and magnetic properties of Fe-N-X ( where X denotes an additive element ). The Sm<SUB>2</SUB>Fe<SUB>17</SUB>N<SUB>3</SUB> is a new type of magnet material which is prepared by introducing nitrogen atoms into the interstitial sites of the Sm<SUB>2</SUB>Fe<SUB>17</SUB> crystal under a nitrogen-containing atmosphere at elevated temperatures. The Sm<SUB>2</SUB>Fe<SUB>17</SUB>N<SUB>3</SUB> shows excellent intrinsic magnetic properties (saturation magne-tization M<SUB>s</SUB> = 1.57 T, the anisotropy field H<SUB>a</SUB> = 21 MA/m and Curie temperature T<SUB>c</SUB> = 746 K). The value of the theoretical maximum energy product, (BH)<SUB>max</SUB> amounts to 490 kJ/m<SUP>3</SUP>, being a match for the one of the Nd<SUB>2</SUB>Fe<SUB>14</SUB>B. We have succeeded in developing high performance Sm-Fe-N bonded-magnets; compression-molding magnet with (BH)<SUB>max</SUB> of 160 kJ/m<SUP>3</SUP> and injection-molding magnets with 110 kJ/m<SUP>3</SUP> have been fabricated so far. Mn-added Sm-Fe-N compacted powder magnet comprised of coarse powder has also been obtained. The Mn-added magnet has good thermal stability and excellent oxidation-resistance.
粉体および粉末冶金 43(1), 59-65, 1996-01-15
Japan Society of Powder and Powder Metallurgy