MECHANICALLY ALLOYED NANOCOMPOSITE MAGNETS

The magnetic and structural properties of mechanically alloyed Nd2Fe14 B+ (Fe, FeCo) powders have been investigated over a wide range of temp eratures. X-ray diffraction patterns on samples milled for 48 h showed that the powders had a two-phase structure consisting of a disordered Nd-Fe-B alloy and alpha-Fe with a fine grain size about 140 angstrom. Enhanced magnetic remanence in the range of 95-105 emu/g with reduced remanence alpha=M(r)/M(s)=0.60-0.68 and a coercivity H(c)=4-6 kOe hav e been obtained-after annealing at 650-750-degrees-C. This behavior is the result of an exchange coupling between the hard and soft phases w ith small grain sizes, about 500 and 200 angstrom, respectively.