THERMAL-BEHAVIOR OF THE INITIAL PERMEABILITY IN SOFT-MAGNETIC NANOCRYSTALLINE ALLOYS

Initial permeability thermograms for soft magnetic nanocrystalline all oys show two characteristic peaks: the first corresponds to the Curie temperature (T-c) of the remaining amorphous phase and the second to t he as-precipitated bcc phase. The former one shows a broad distributio n and in general shifts with annealing towards lower temperatures comp ared to the T-c of the as-quenched amorphous state. The latter one Is relatively sharp and shifts with annealing towards higher temperatures but disappears before reaching the T-c of the equilibrium bcc phase. The first and second peaks are explained by the effect of the inhomoge neous chemical composition of the remaining amorphous phase and by the superparamagnetic transition of the dipolar (and/or exchange)-coupled bcc nanograins respectively, both changing with the evolution of anne aling.