Magnetic Softening and Hardening in Metglas® 2605SC at the Onset of Nanocrystallization

Moessbauer spectroscopy, coercive field and permeability were used to study the transformations produced by annealing at 375 C as-quenched amorphous ribbons of Metglas{reg_sign} 2605 SC of nominal composition Fe{sub 81}B{sub 13.5}Si{sub 3.5}C{sub 2}. The coercive field showed a decrease (softening) in the 0--30 min range, followed by an increase (hardening) for annealing times above 30 min. Permeability exhibited the opposite behavior, with a maximum for about 30 min. The Moessbauer magnetic hyperfine spectra showed variations in the intensities ratios, which were related with macroscopic measurements in good agreement with the softening-hardening processes.