CRYSTALLIZATION OF THE METALLIC-GLASS FE78B13SI9

The microstructures and kinetics with heating for an amorphous Fe78B13Si9 alloy were studied by X-ray diffraction, transmission electron microscopy, differential thermal analysis and differential scanning calorimetry. The first crystallization takes place by the simultaneous formation of alpha-(Fe,Si) and Fe3B having the shapes of dendrite and spherulite, respectively. Metastable Fe3B then transformed into a stable phase of Fe2B at a higher temperature. The activation energy for crystallization and the Avrami exponent were determined. It was found that crystallization behaviour in Fe78B13Si9 is controlled by nucleation rather than growth.