CRYSTALLIZATION OF FE73.5CU1NB3SI13.5B9 - STRUCTURE AND KINETICS EXAMINED BY X-RAY-DIFFRACTION AND MOSSBAUER-EFFECT SPECTROSCOPY

Changes in the structure of the amorphous alloy Fe73.5Cu1Nb3Si13.5B9 were investigated after annealing for 1 h in a temperature range from 450-800-degrees- using x-ray diffraction scattering and Mossbauer effect spectroscopy. Between 520 and 550-degrees-C nanocrystalline Fe80Si20 grains with the DO3 structure (diameter of about 10 nm) are embedded in an amorphous grain boundary phase. Above 650-degrees-C the grain size increases and the amorphous grain boundary phase disappears. The Fe-B phases form and a new paramagnetic phase is observed. Furthermore the kinetics of the amorphous-to-nanocrystalline phase transition of this alloy was examined by x-ray diffraction observing the development of crystallization with time at a fixed annealing temperature of 520-degrees-C. The beginning of crystallization appears at times less than 2 min, most grains developing in the first 10 to 20 min while after about 5 min the grain size remains constant with a diameter of about 10 nm.