M. Ito et al., IMPROVEMENT OF MAGNETIC-PROPERTIES OF MEC HANICALLY GRINDING GROUND SM2FE17NX POWDERS BY VACUUM HEAT-TREATMENT, Nippon Kinzoku Gakkaishi, 59(11), 1995, pp. 1172-1177
Sm2Fe17Nx permanent magnetic powders have been prepared by mechanical
grinding (MG) and subsequent heat treatments for crystallization and n
itriding. Sm2.5Fe17 and Sm2.3Fe17 alloy powders have been used as a st
arting material. The oxygen content of the powders crystallized in vac
uum is less than that of the powders crystallized in Ar atmosphere: it
is less than 9000 ppm for the Sm2.5Fe17 powders. Consequently, the pr
ecipitation of alpha-Fe, which deteriorates the rectangularity of thei
r demagnetization curves, is suppressed. After MG for 72 ks and crysta
llization in vacuum the nitrided Sm2.3Fe17 powders close to stoichiome
tric Sm2Fe17, has also no alpha-Fe precipitation. The saturation magne
tization and remanence are larger than those of the nitrided Sm2.5Fe17
powders.