CRYSTALLIZATION AND MAGNETIC-PROPERTIES OF FE84B9NB7 AMORPHOUS RIBBONS

The amorphous Fe84B9Nb7 and its nanocrystallization have been studied by x-ray, Mossbauer spectroscopy and magnetic moment measurements. The average hyperfine field H-hf(T) of the amorphous state shows a temper ature dependence of [H-hf(T)-H-hf(0)]/H-hf(0) = -0.52(T/T-C)(3/2)-0.34 (T/T-C)(5/2) for T/T-C < 0.7, indicative of spin-wave excitation. The quadrupole splitting just above the Curie temperature T-C is 0.41 mm/s , whereas the average quadrupole shift below T-C is zero. The Curie an d crystallization temperatures are determined to be T-C = 330 K and T- x = 750 K, respectively, for a heating rate of 5 K/min. The occupied a rea of the nanocrystalline phase at the optimum annealing temperature is about 73%.