Magnetic and magnetoelastic response of stress cycled Terfenol-D

The changes in magnetic and magnetomechanical properties of grain-oriented Terfenol-D have been monitored after stress cycling. Measurements of B–H loops and differential permeabilities under uniaxial preloads (⩽20 MPa) applied along the [112] axis show that magnetic anisotropy is induced after ∼106 cycles of ±100 MPa about a mean preload of 120 MPa. According to the permeability data, magnetic moments lie preferentially along the 〈111〉 axes, normal to the [112] grain growth direction, and with the subsequent application of field along the [112] axis magnetic moment rotation is enhanced. This magnetic response is virtually identical to that induced by the application of measurement preloads and to results of earlier work on magnetic annealing. The magnetomechanical coupling data show little variation from the value prior to stress cycling (k33∼60%) provided the measurement preloads and bias fields are adjusted accordingly. The reasons for the observed modified behavior after stress cycling are discusse...