Magnetic anisotropy in (Fe, Co) 75Si 15B 10 and (Fe 0.11Co 0.89) 72Mo 3Si 15B 10 metallic glass ribbons, induced by constant stress and constant strain annealing

Abstract

The magnetic anistropy induced by constant tensile stress and constant torsional strain annealing has been studied for liquid quenched alloys of the compositions (Fe x Co 1− x ) 75Si 15 B 10 ( x = 0.1−1.0) and (Fe 0.11Co 0.89) 72Mo 3Si 15B 10. Within a certain annealing temperature range (depending on composition, pre-annealing time, applied stress and stress-annealing duration) the induced easy axis is perpendicular to the ribbon axis. After subsequent stress relief the easy axis turns parallel to the ribbon axis. The easy ribbon axis anisotropy produced in this way reveals a similar composition dependence as the anisotropy obtained by magnetic field annealing, but the anisotropy constant may be up to one order of magnitude larger, depending on the stress annealing conditions. In contrast to the field anneal induced anisotropy, the stress anneal induced anisotropy can be made permanent in the sense that it still remains after subsequent stress relief. It is furthermore shown that constant strain annealing induced anisotropy can be deduced from the properties observed after constant stress annealing, and a method for selecting proper stress relaxation conditions, with the purpose of obtaining maximum magnetic softness (isotropy) is proposed.