Production of Sm–Fe–N bulk magnets by the spark plasma sintering method with dynamic compression

• A method called the spark plasma sintering with dynamic compression is proposed.
• Sm–Fe–N powder was consolidated into bulk materials at low temperatures.
• A Sm–Fe–N magnet produced at 623 K exhibited a high coercivity of 0.73 MA/m.

We report a modified spark plasma sintering method, called spark plasma sintering with dynamic compression (SPS-DC). In the present study, TbCu7-type Sm–Fe–N powder was consolidated into bulk materials of up to 823 K using this method. The Sm–Fe–N powder was successfully consolidated into bulk materials at low temperatures of 573–623 K. It was found that the Sm–Fe–N magnets produced at these low temperatures retained the TbCu7 phase without any appreciable decomposition of that phase. The magnetic properties of the Sm–Fe–N magnet produced at these low temperatures were comparable to those of the Sm–Fe–N powder. The Sm–Fe–N bulk magnet produced at 623 K exhibited a high remanence of 103 A m2/kg with a high coercivity of 0.73 MA/m.