Magnetic properties of Sm–Fe–N anisotropic magnets produced by magnetic-field-assisted spark plasma sintering

Sm–Fe–N magnets were successfully produced at temperatures below 773 K by magnetic-field-assisted spark plasma sintering. The resultant magnets had high densities of 88.7–92.5%. Although partial decomposition of the Sm2Fe17N3 phase was observed in the Sm–Fe–N magnets, the decomposition was significantly lowered by the addition of a small amount of Zn powder to the Sm–Fe–N powder. The resultant Sm–Fe–N magnets containing 5 wt.% Zn and 10 wt.% Zn exhibited higher coercivity than the Sm–Fe–N magnets. X-ray diffraction studies and magnetic measurements confirmed that the Sm–Fe–N magnets and those containing 5 wt.% Zn and 10 wt.% Zn were magnetically anisotropic. A high value of 158 kJ/m3 was achieved for the maximum energy product when Sm–Fe–N powder containing 5 wt.% Zn was sintered at 723 K by magnetic-field-assisted spark plasma sintering.