ENHANCED REMANENCE IN FLASH-ANNEALED ND4FE78B18

Nanocrystalline Nd4Fe78B18 was produced by affixing current leads dire ctly to amorphous ribbons for flash-annealing. Ribbons were annealed i n the range T-a = 650-1000 degrees C, for times 10-600 s. Flash-anneal ed ribbons show higher remanence ratios (M(r)/M(s) congruent to 0.83) than those submitted to conventional furnace (680 degrees C/10 min) an nealing (M(r)/M(s) congruent to 0.74). In flash-annealed ribbons, Moss bauer spectroscopy and x-ray diffraction indicated the presence of the Nd2Fe23B3 phase, in addition to Fe3B, Nd2Fe14B, and alpha-Fe. Flash-a nnealing for short times at high temperatures may give H-c values up t o 20% higher than furnace annealing. The isothermal remanent magnetiza tion and the dc demagnetization remanence were found to be in reasonab le agreement with the Wohlfarth relation.