Structures and magnetic properties of Nd-Fe-B bulk nanocomposite magnets produced by the spark plasma sintering method

摘要

We studied the effects of the sintering temperature and applied pressure on Nd-Fe-B bulk nanocomposite magnets produced by the spark plasma sintering (SPS) method. Amorphous Nd_4Fe_(77.5)B_(18.5) melt-spun ribbons were successfully consolidated into bulk form by the SPS method. When sintered at 873 K under applied pressures between 30 and 70 MPa, the bulk materials consisted of nanocomposite materials with a soft magnetic Fe_3B phase and hard magnetic Nd_2Fe_(14)B phase. The density and magnetic properties of the bulk materials sintered at 873 K were strongly dependent on the applied pressure during sintering. Bulk Nd_4Fe_(77.5)B_(18.5) nanocomposite magnets sintered at 873 K under an applied pressure of 70 MPa showed a high remanence of 9.3 kG with a high coercivity of 2.5 kOe.