Transverse anisotropy field and lattice plane anisotropy of stress annealed Fe-Cu-Nb-Si-B ribbons

The transverse magnetic anisotropy and lattice plane anisotropy of stress-annealed Fe-Cu-Nb-Si-B amorphous ribbons have been studied. The GMI effect or impedance ratio decreased gradually with increasing applied tensile stress. The transverse anisotropy field (Hk) corresponded to the full width at half maximum (FWHM) of the GMI curves. A linear response was found between the applied tensile stress (σ) and the transverse anisotropy field (Hk), and it was seen from the linear expression that annealing without stress resulted in a very small Hk of ∼200 A/m. We also calculated the strains from the elongations obtained during the stress annealing process, the results showed that the strain and applied stress were linearly related and for a zero-tensile stress, the elastic strain was negative (−0.0219) showing that contraction dominates during annealing without tensile stresses. The lattice plane anisotropy (Δd) calculated from XRD peaks was also linearly related to the applied tensile stress. The lattice spacing in the direction parallel to the tensile stress was elongated while the lattice spacing in the direction perpendicular to the tensile stress was compressed.