Abstract
The preparation of Sm2Fe17Nx permanent magnetic powder whose grain size is finer than the single magnetic domain size of about 300nm has been tried by mechanical grinding (MG) and the subsequent heat treatment and nitriding. Heat treatment in vacuum reduced the content of oxygen in the speciemen compared with heat treatment in Ar. The nitrided powder after annealed in vacuum was improved in coercivity and the rectangularity compared with the nitrided powder after annealed in Ar. The remanence and rectangularity of the nitrided Sm2.3Fe17Nx specimen after annealed in vacuum were superior to those of the nitrided Sm2.5Fe17Nx specimen after annealed in vacuum. TEM and SEM photographs showed that the vacuum-annealed and nitrided powder after 72ks-MG was composed of mixed grains of 20-100nm.
