FIZIKA A 5 (1996) 4, 185-196

INFLUENCE OF THE SUCCESSIVE ANNEALING ON THE MAGNETIZATION PROCESSES IN Fe_73.5Cu₁Nb₃Si_15.5B₇ RIBBON

STJEPAN SABOLEK, ŽELJKO MAROHNIĆ^a and GISELHER HERZER^b
Department of Physics, Faculty of Science, University of Zagreb, POB 162, Zagreb, Croatia
^aInstitute of Physics of the University, University of Zagreb, POB 304, Zagreb, Croatia
^bVacuumschmelze GmbH, D-63450 Hanau, Germany

Received 21 November 1996

The model for the influence of core-current generated field H_p on the magnetization processes in ferromagnetic ribbons has been employed for the detailed analysis of the M-H loops and the corresponding dM/dt vs. H curves for Fe_73.5Cu₁Nb₃Si_15.5B₇ alloy, successively annealed at different temperatures T_a Ł 540 ^°C. The analysis shows that in the amorphous state (T_a Ł 300 ^°C), only fraction of the main (inner) domain structure participates in the process of magnetization. Further annealing strongly reduces the local anisotropy and the average pinning strength of the domain walls < S_u > , which results in a very low coercive field H_c for 400  ^°C Ł T_a Ł 500 ^°C. Simultaneously, the maximum magnetization M_m becomes almost equal to the saturation magnetization M_s ( » 1.3 T) already in low magnetizing field (H₀ = 100 A/m). The minimum of H_c (T_a = 450 ^°C) is associated with the formation of nanocrystalline Fe₃Si grains, and high M_m and maximum permeability m_max and a low angle < d > (between domain magnetizations and the ribbon axis) show that a whole domain structure is very simple in this range of T_a. Further annealing (T_a > 500 ^°C) increases < S_u > and < d > (which increases H_c) and reduces drastically m_max which is consistent with the earlier results for similar samples.

UDC 538.955
PACS 75.50.Kj, 75.60.-d, 75.60.Ch

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