engleski

Domain Structure, Pinning Centres and Magnetization Processes in Amorphous and Nanocrystalline Fe73.5Cu1Nb3Si15.5B7 Ribbon

A detailed analysis of the M-H loops and the corresponding dM/dH versus H curves for a Fe73.5Cu1Nb3Si15.5B7 ribbon has been performed for different stages of successive annealing (T-a less than or equal to 540 degrees C). The application of the model for the influence of the core current generated fields H-p on the process of magnetization of ferromagnetic ribbons showed that in the amorphous state (T-a less than or equal to 300 degrees C) only a 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 degrees C less than or equal to T-a less than or equal to 500 degrees C. Simultaneously, the maximum magnetization M-m becomes almost equal to the saturation magnetization M-s (approximate to 1.3 T) already in low magnetizing field (H-0 = 100 A/m). The minimum of H-c (T-a = 450 degrees C) is associated with the formation of nanocrystalline Fe3Si grains. High M-m and maximum permeability mu(max) and a low angle [delta] (between the domain magnetizations and the ribbon axis) shows that the whole domain structure is very simple in this range of T-a. Further annealing (T-a > 500 degrees C) increases [S- u] and [delta] (which increases H-c) and reduces drastically mu(max) which is consistent with the earlier results for similar samples.

domain structure ; pinning centres ; nanocrystalline Fe_73.5Cu_1Nb_3Si_15.5B7 ribbon

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