Correlation between magnetic properties and microstructures of die-upset forged Fe-RE-B magnets and initial melt-spun ribbon

The magnetic properties of hot pressed and die-upset forged Fe-RE-B magnets made from melt spun ribbons are studied in relation to the microstructure of the initial ribbon. It is found that the best properties are exhibited by magnets processed from optimally quenched nanocrystalline ribbons. The magnets processed from both underquenched and overquenched (amorphous) ribbons give inferior magnetic properties due to the presence of coarse grains resulting from a low quenching rate for the former and from a low crystal nucleation frequency in amorphous alloy during processing for the latter.<>