Nanocrystallization behavior and magnetic properties of amorphous Fe78Si9B13 ribbons

The amorphous state of ferromagnetic Fe78Si9B13 ribbons and its nanocrystallization were investigated by in situ transmission electron microscope (TEM), X-ray diffraction (XRD), Mossbauer spectroscopy (MS), differential scanning calorimeters (DSC) and magnetic moment measurements. The Mossbauer spectrum exhibited an essentially symmetric hyperfine held pattern of 259 kOe in as-quenched amorphous state at room temperature. The Curie and crystallization temperature were determined to be T-C = 708 K and T-x = 803 K, respectively. The T-x value was in good agreement with DSC measurement results. The occupied fraction of the nanocrystalline phases of alpha-Fe(Si) and Fe2B at in situ optimum annealing temperature was about 57% and 43%, respectively. It is notable that the magnetization of the amorphous phase decreases more rapidly with increasing temperature than those of nanocrystalline ferromagnetism, suggesting the presence of the distribution of exchange interaction in the amorphous phase or high metalloid contents. (C) 2000 Elsevier Science B.V. All rights reserved.