MAGNETIC-PROPERTIES OF HIGH-QUALITY MELT SPUN DIDYMIUM IRON COBALT BORON RIBBONS AND THEIR BONDED MAGNETS

Melt-spun ribbons of Didymium-Fe-Co-B system alloys were prepared by the single roller rapid-quenching method. The effects of composition, substrate surface velocity and heat-treatment on the magnetic properties were studied. The magnetic properties of their isotropic compressed bonded magnets made of the optimum annealing condition ribbons were also measured. A maximum energy product of 149.1kJ/m3was obtained for 27wt%R-64.4wt%Fe-7wt%Co-1.6wt%B(R=Didymium) alloy ribbon prepared at a substrate surface velocity of 17.1m/s. The amorphous 27wt%R-64.4wt%Fe-7wth1.6wt%B ribbons prepared at a substrate surface velocity of 20.7m/s were crystallized by annealing treatment, and the optimun annealing condition was found to be at 650°C for 20min. Its corresponding value of (BH)max was 134.2kJ/m3. The value of (BH)m axfor the 27wt%R-64.4wt%Fe-7wt%Co-1.6wt%B bonded magnet prepared by using the ribbons annealed at 650°C for 20min was 88.2kJ/m3. © 1990 IEEE