Magnetoelastic effects on practical properties of amorphous ribbons

Magnetoelastic effects are observed on Epstein sample of Metglas 2605S2 when additional weights are used to reduce the gap at the corner joints of the magnetic path. The measured degradation of the apparent power is important though the exerted pressure remains lower than 4 kPa. This effect is explained taking into account the ribbon shape which is not perfectly flat. The weights submit the end of the strips to considerable bending stresses responsible for the magnetic properties degradation. By flattening the sample during annealing the weight influence is largely reduced. This study shows that the achievement of the best magnetic properties of a stacked core requires special annealing conditions which are difficult to obtain. A stress annealing is necessary to flatten the strips, failing which ribbon stacking causes an appreciable decrease in the magnetic performance of the material.