Effect of applied stress on the magnetization of amorphous magnetoelastic wires

The magnetization of transversely annealed metallic glass wires (Fe_77.5B₁₅Si_7.5) was examined as a function of longitudinal stress and torsional strain. The effect of annealing parameters on magnetoelastic coupling of the wires was measured. The wires differ from ribbons of similar composition in several important respects. The domain configuration appears to consist of a longitudinally oriented core region surrounded by a sheath consisting of transverse domains. The surface transverse domains were directly observed by an optical imaging technique. Magnetization of unstressed wires proceeds by a two-step process. Application of 3 MPa stress alters the domain configuration, leading to longitudinal 180° domain walls throughout the wire. The additional imposition of torsional strain leads to a subcritical bifurcation. It was found that, unlike ribbons, wires annealed with the magnetic field off during the heating portion of the annealing cycle have different magnetoelastic properties from samples annealed with the field on throughout the annealing process