A magnetoelastic study of a transverse creep-induced magnetic anisotropy in an FeNb-based amorphous alloy

The hard ribbon axis anisotropy induced in the magnetostrictive amorphous alloy Fe74.7Nb3Si12.8B9.5 by stress annealing at temperatures 633-693 K and under tensile stresses up to 204 MPa has been studied by several experimental methods (measurement of de hysteresis loops, field dependence of engineering magnetostriction lambda(e) and Young's modulus E, and domain structure observations). The experimental data are discussed in terms of the phenomenological model developed earlier by Squire. The most significant improvement in the magnetoelastic response was found for the highest annealing temperature T-a = 693 K. The maximum Delta E effect (27%) observed is much lower than the maximum estimated theoretical value (87%), The lambda(e) and domain studies suggest that this difference is most probably due to the dispersion of easy axes and/or anisotropy values. Even though the phenomenological model does not take into account local variations in the anisotropy, it gives a reasonable quantitative description of a slightly perturbed hard ribbon axis case.