PRECIPITATION AND DEFECTS IN Nb-CONTAINING NdDyFeCoB MAGNETS

The microstructure of Nb-containing NdDyFeCoB magnets has been investigated using transmission electron microscope. Very small particles whose diameters are about several to 40Å have been found in as-sintered magnets. It may be formed by self-tempering. Dislocations and stacking faults have been found inside grains. It seems that the increase of coercive field in Nb-containing magnets is closely related with defects and precipitations.