Production of Sm–Fe–N bulk magnets by spark plasma sintering method

• Sm–Fe–N powders were successfully consolidated into bulk magnets by the SPS method.
• TbCu7-type powder was more stable than Th2Zn17-type powder during sintering.
• The TbCu7-type magnets had higher density than the Th2Zn17-type magnets.
• The TbCu7-type magnet produced at 773 K exhibited a high coercivity of 0.72 MA/m.

Th2Zn17-type and TbCu7-type Sm–Fe–N powder were consolidated into bulk magnets by the spark plasma sintering (SPS) method. It was found that the coarse TbCu7-type Sm–Fe–N powder possessed greater stability during sintering than the fine Th2Zn17-type Sm–Fe–N powder. Although the TbCu7-type magnets produced at temperatures exceeding 773 K showed a low coercivity comparable to that of the Th2Zn17-type magnets, they exhibited a higher coercivity than the Th2Zn17-type magnets when produced at 773 K or lower. The TbCu7-type magnet produced at 773 K exhibited a high remanence of 96.4 Am2/kg with a high coercivity of 0.72 MA/m.