Compositional Dependence of Structure and Crystallization of Fe-B-Si Amorphous Alloys Studied by Mössbauer Spectroscopy

Fe90−xBxSi10 amorphous alloys containing 10∼17 at%B were studied by 57Fe Mössbauer spectroscopy. The internal magnetic field distribution which was derived from the observed spectrum by a Fourier analysis was approximated by a sum of three Gaussian lines with the average internal fields of about 15.9 MA/m (component A), 19.9 MA/m (component B) and 23.9 MA/m (component C). With increasing boron content, the component A increases and the component C decreases. The intensity of the component A sharply increases from the composition of about 13 at% boron which is slightly higher than the eutectic composition. The component B increases to a maximum at about 13 at% boron and then decreases at higher boron contents. The compositional dependence of the fraction and the average internal field of each structural component suggests that the components A and B have Fe2B-like and Fe3B-like short range orders, respectively, and the component C has a lower boron content and a relatively high Si content of about 9 at%. The results of DSC and Mössbauer effect measurements on annealing Fe80B10Si10 and Fe76B14Si10 amorphous alloys suggest that the nucleations of the Fe2B intermatallic compound and the α-Fe(Si) solid solution take place in the regions of components A and C, respectively.