Influence of the successive annealing on the magnetization processes in Fe73.5Cu1Nb3Si15.5B7 ribbon.
The model for the influence of core-current generated field Hp 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 Fe73.5Cu1Nb3Si15.5B7 alloy, successively annealed at different temperatures Ta 540 ° C. The analysis shows that in the amorphous state (Ta 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 < Su > , which results in a very low coercive field Hc for 400 ° C Ta 500 ° C. Simultaneously, the maximum magnetization Mm becomes almost equal to the saturation magnetization Ms ( ≫ 1.3 T) already in low magnetizing field (H0 = 100 A/m). The minimum of Hc (Ta = 450 ° C) is associated with the formation of nanocrystalline Fe3Si grains, and high Mm and maximum permeability mmax 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 Ta. Further annealing (Ta > 500 ° C) increases < Su > and < d > (which increases Hc) and reduces drastically mmax which is consistent with the earlier results for similar samples.
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