Magnetomechanical Damping in Iron—Silicon Alloys

Abstract

Experiments with iron‐4% silicon wires containing preferred orientation with the 〈110〉 direction along the axis showed that under these conditions, extremely high magnetomechanical damping can be achieved at low strain levels in a torsion pendulum. The effect of crystallographic orientation on the damping was brought out by experiments on wires of square cross section of grain‐oriented commercial iron‐3% silicon alloy. Internal stress, produced by occluded hydrogen, markedly reduced the magnetomechanical damping in the iron‐4% silicon alloy but recovery began to take place after several days at room temperature. Changes in magnetic induction produced during the torsional oscillations by the inverse Wiedemann effect were measured to obtain an indication of the domain boundary movements. These latter experiments together with the damping experiments support the Summer and Entwistle model for the relationship between the magnetic field at maximum susceptibility, the saturation magnetization, the saturation magnetostriction, and the strain at which maximum damping occurs.