Abstract:The high current density electropulsing and comparable isothermal annealing were used to treat the amorphous Fe_73.5Cu₁Nb₃Si_13.5B₉ alloy, and the structure of the treated samples was examined using Mossbauer spectroscopy, XRD and TEM. Experimental results showed that nanocrystallization occurs in the amorphous Fe_73.5Cu₁Nb₃Si_13.5B₉ at the temperature of 420 ℃during electropulsing. No Fe-B phase was observed and no ordered DO₃ structure was detected in the crystallized Fe_73.5Cu₁Nb₃Si_13.5B₉ sample. The disordered α-Fe(Si) phase with grain size of 8～9nm amounts to 30.9%. The Si atom concentration in α-Fe(Si) phase was estimated to be about 17.6% according to calculation based on binomial distribution .Area ratios, A_2.5/A_1.6, in the as-quenched sample and annealed sample were 0.92, but increased to 0.97 in the residual amorphous phase of the electropulsed sample, showing that the magnetic moment of Fe atoms in the residual amorphous remains the in-plane anisotropy, in spite of bulk nanocrystallization. In contrast with the result by comparable isothermal annealing, it was concluded that the transformation of the amorphous Fe_73.5Cu₁Nb₃Si_13.5B₉ to nanocrystalline induced by high current density electropulsing is a new method for nanocrystallization of the amorphous alloy, different from the flash annealing method and also from the conventional isothermal annealing method.

Key words: amorphous Fe_73.5Cu₁Nb₃Si_13.5B₉; electro-pulsing; nanocrystallization.