Correlation between stress relaxation induced anisotropy, magnetic domain, and permeability of Co-doped FeCuSiBNbMn alloys

The effect of Co contents on the permeability, magnetic anisotropy, and structure has been investigated for FeSiBNbCuMn amorphous alloys during annealing with and without tensile stress. Large stress relaxation induced anisotropy (Ku) of 482.0-1485.4 J/m3 is observed with an easy axis perpendicular to the direction of tensile stress (i.e., ribbon axis), which results in constant permeability of 1-2.8 x 103 at 1 kHz 1 MHz. Different from the irregular domain structure in the samples annealed without tensile stress, stress annealing generates regular domains and 180 degrees straight walls, and domain width increases with the increases of Co contents. Besides, the correlation between permeability, induced anisotropy, and domain width is established. These results could provide a good guide for improving the frequency stability of permeability by adjusting anisotropy and domain structure.