Abstract
Nanocrystalline bulk Fe88Nb2Nd5B5 and Fe86Nb2Nd7B5 alloys were made by consolidating amorphous powders with a spark-plasma-sintering method and subsequent annealing. Bulk alloy made by consolidating amorphous powders has a higher density than that made by consolidating crystalline powders, presumably because the amorphous alloy softens around the crystalline temperature. Bulk Fe88Nb2Nd5B5 and Fe86Nb2Nd7B5 alloys made by consolidating amorphous powders at a temperature of 873 K and a pressure of 636 MPa have a density of 7.5 g/cm3, and form a nanocrystalline composite structure of bcc-Fe, Fe3B, and Nd2Fe14B phases with grain sizes of 20-40 nm after annealing at 1023K. Nanocrystalline bulk alloys show hard magnetic properties, remanence (Jr) of 0.83-1.0 T, coercive force (HcJ) of 190-290 kA/m, and maximum energy product (BH)max of 43-49 kJ/m3.
