Nanocrystallization behavior and magnetic properties of amorphous Fe78Si9B13 ribbons

The amorphous state of ferromagnetic Fe78Si9B13 ribbons and its nanocrystal lization were investigated by in situ transmission electron microscope (TEM ), X-ray diffraction (XRD), Mossbauer spectroscopy (MS), differential scann ing calorimeters (DSC) and magnetic moment measurements. The Mossbauer spec trum exhibited an essentially symmetric hyperfine held pattern of 259 kOe i n as-quenched amorphous state at room temperature. The Curie and crystalliz ation temperature were determined to be T-C = 708 K and T-x = 803 K, respec tively. The T-x value was in good agreement with DSC measurement results. T he occupied fraction of the nanocrystalline phases of alpha-Fe(Si) and Fe2B at in situ optimum annealing temperature was about 57% and 43%, respective ly. It is notable that the magnetization of the amorphous phase decreases m ore rapidly with increasing temperature than those of nanocrystalline ferro magnetism, suggesting the presence of the distribution of exchange interact ion in the amorphous phase or high metalloid contents. (C) 2000 Elsevier Sc ience B.V. All rights reserved.