Sm_2Fe_(17) and Sm_(10.5)Fe_(88.5)Zr_(1.0) prealloys were prepared by melting in a vacuum arc furnace. The
nitrogenation
was carried out in ultra pure nitrogen, while the cast Sm_2Fe_(17) was additionally homogenized. The
nitrogenation behaviour was investigated by using scanning electron microscopy and X-ray diffraction technique. Diffusion experiments on thin plates showed that the diffusion of nitrogen in Sm_2Fe_(17) was faster than it in Sm_(10.5)Fe_(88.5)Zr_(1.0).The sufficient nitrogenation time for Sm_2Fe_(17) and Sm_(10.5)Fe_(88.5)Zr_(1.0) spherical particles of 20μm diameter would be 10h and 16h respectively, according to the theoretical
calculations by using Fick second law. The nitrogenation time to obtain fully nitrided alloy for factual powders was less than predicted by calculations. The difference between the idealized powders used for theretical calculations and real powders was attributed to the particle size distribution, surface state, microcracks caused by nitrogenation and the factual condition of the milled powder. For the spherical particles of 20μm diameter, the nitrogenation was accomplished basically when the time was 6h. Sm_2Fe_(17)N_x would decompose if the nitrogenation time was too long.