Stress-annealing induced anisotropy in FeCrCuNbSiB nanocrystalline wires

Abstract

After suitable annealing, amorphous alloy with composition of FeCuNbSiB (Finemet) exhibits excellent soft magnetic properties owing to the nanocrystallization. When the amorphous alloy was annealed under application of mechanical stress, a transverse anisotropy of the order of 103 J/m3 had been found in the nanocrystalline alloy. During the annealing process, with an axially applied tensile stress, the nanocrystalline bcc Fe-Si grains (magnetostriction ls <; 0) take the form of ellipsoid with the short axis parallel to the axis of samples due to the magneto-elastic interaction in the interface of two-phases. Since the load is still applied in the process of cooling, this microstructure can be reserved in the stress-annealed samples. In this work, the stress-annealing induced anisotropy of Cr-doped Finemet nanocrystalline wires is studied, especially, an anomalous stress-dependent induced anisotropy is reported.