Synchrotron radiation analysis of structure and magnetism of grain boundary phase in Nd-Fe-B sintered magnet

摘要: Grain size reduction technique of Nd-Fe-B sintered magnets is well known process to increase a coercivity without substitution of Dy for Nd. We have been developing ultrafine grained Nd-Fe-B sintered magnets using a helium gas jet-mill which can produce smaller particle size of the powder than a conventional nitrogen gas jet-mill (1). Recently, Nakamura et al.(2) have reported the development of single crystal powders with particle size of under 0.6 µm using a combination of HDDR (hydrogenation-disproportionation-desorption-recombination), hydrogen decrepitation, and the helium gas jet-mill processes. In the present study, we report magnetic properties of ultrafine-grained Nd-Fe-B sintered magnets with grain size of under 1 µm.