Enhanced differential magnetostrictive response in annealed Terfenol-D

Abstract

The field and pressure dependencies of the magnetostriction of Tb0.316Dy0.684Fe1.982 have been measured in a grain-oriented rod after thermally annealing for 1 day at 850 °C and for 4 days at 950 °C in an argon atmosphere. The results of the heat treatment are a fivefold increase in the strain coefficient d33(=dλ/dH) and a 100% increase in the maximum strain (λ). There was also an increase in the λ-vs-H hysteresis. Under compressive uniaxial stress there was virtually no bulk change in magnetostrictive strain until the field exceeded a critical value which depended on the applied stress, for instance ∼12 kA/m under a stress of 6 MPa.