MICROSTRUCTURAL CHARACTERIZATION OF FE80B20 EUTECTIC SPHERULITES BY SMALL-ANGLE NEUTRON-SCATTERING AND TRANSMISSION ELECTRON-MICROSCOPY

The evolution of the microstructure during the crystallization of amor phous Fe80B20 alloys has been investigated by small-angle neutron scat tering (SANS) and transmission electron microscopy (TEM). Samples with an increasing degree of crystallization were obtained by performing d ifferent isothermal heat treatments on melt spun amorphous ribbons. Th e TEM measurements indicate that the crystallization occurs by nucleat ion and growth of Fe3B spherulites which include small finely divided alpha-Fe acicular crystallites. On the basis of the TEM results a mode l for the quantitative analysis of the SANS data has been formulated. The results show that, due to the high growth velocity of the nucleate d particles, only their number increases with increasing annealing tim e, while their size and internal structure is not dependent on the deg ree of crystallization. (C) 1996 American Institute of Physics.