STRUCTURE INVESTIGATIONS ON ANNEALED FE(CUNB)SIB ALLOYS WITH DIFFERENT SI-B CONTENTS

The structure of three alloys Fe73.5Cu1Nb3Si22.5-zBz with z = 5, 9, and 14 is examined in the nano- and microcrystalline states. This alloy system is very interesting for technical applications because of its nanostructure causing very soft magnetic properties together with low magnetostriction. The Si and B concentrations influence the number and the temperature of phase transitions as well as the grain size, composition, and structure of the nano- and microcrystals which develop while annealing the as-cast amorphous alloys. The specific electrical resistivity and magnetization are measured as function of temperature at well-defined heating rates. These measurements allow to determine characteristic temperatures which indicate the phase formation of nano- and microcrystals. Furthermore the Curie temperatures of phases being ferromagnetic are helpful for phase identification. The detailed phase analysis of differently annealed samples is done by X-ray diffraction and Mossbauer spectroscopy. The combination of hyperfine field and diffraction data allows us to ensure the existence of new phases.