NANOSTRUCTURED ND-FE-B MAGNETS WITH ENHANCED REMANENCE

Nanostructured isotropic Nd-Fe-B magnets with enhanced remanence were produced by hot compaction of mechanically alloyed Nd-Fe-B powders at temperatures of about 600 degrees C. Phase formation occurred during h ot pressing without significant grain growth. The microstructure is a two phase nanocomposite of hard magnetic Nd2Fe14B and soft magnetic al pha-Fe with an average grain size of about 20 nm. These small dimensio ns allow effective exchange interactions between hard and soft magneti c grains and result in an enhancement of the remanence by more than 30 % above the Stoner-Wolfarth limit expected for noninteracting single d omain particles. So far, the best results are a remanence of 1.0 T, an energy density of 121 kJ/m(3) and a coercivity of 4.2 kA/cm for a Nd- Fe-Co-Si-B magnet. (C) 1995 American Institute of Physics.