INFLUENCE OF THE FABRICATION CONDITIONS ON THE HIGH-FREQUENCY MAGNETIC RESPONSE OF MELT-SPUN FE73.5SI13.5B9NB3CU1

The aim of this work is to analyze the influence of the fabrication co nditions on the magnetic properties of Fe73.5Si13.5B9Nb3Cu1 melt-spun nanocrystalline ribbons. Different initial structures, amorphous and p artially crystalline, have been obtained during the rapid solidificati on procedure. The structural characterization shows that a decrease in the quenching rate through a reduction in the tangential wheel veloci ty, gives rise to a partially crystalline state, characterized by the appearance of a textured alpha-FeSi nanocrystalline phase. The occurre nce of the crystalline fraction in the initial as-cast state gives ris e to a magnetic hardening with respect to the amorphous sample casted at higher quenching rate. However, the evolution of coercivity under t hermal treatments is roughly independent of the initial structure. Mor eover. a detailed analysis of the ac susceptibility as a function of a nnealing, temperature shows that the ribbon obtained at lower quenchin g rate presents higher susceptibility values in the optimum magnetic s tate (T-a = 550 degrees C, 1 h) in a wide range of driving frequency ( up to 100 kHz).