The effect of magnetic field heat treatment on magnetostriction of Terfenol-D 2-2 composites

Based on the analysis of the magnetostriction for Terfenol-D composites, Terfenol-D 2-2 magnetostrictive composites have been prepared with laminations perpendicular to [1 1 2] axes. Then one of the samples was annealed in the vacuum at 423K for 15 min at the magnetic field of 240 kA/m, which is along the direction of laminations and vertical to the [1 1 2] axes of the specimen. The static magnetostriction l and dynamic magnetostrictive lambda coefficient d(33) of samples were measured under the compressive stress of 0, 2, 4, 6 and 8 MPa. Effects of the compressive stress and the magnetic field heat treatment on the magnetostriction lambda have been investigated. It is found that the magnetostriction of 2-2 composites can be improved under the compressive stress when the magnetic field is larger than 20 kA/m. The magnetostriction of 2-2 composites with the magnetic field heat treatment increases under compressive stress, and it can reach 1390x10(-6) at the magnetic field of 200 kA/m and under the compressive stress of 4 MPa, much larger than the value of 860x10(-6) without the magnetic field heat treatment. The highest magnetostriction of the 2-2 composite with the magnetic field heat treatment can reach 1530x10(-6). The dynamic magnetostrictive coefficient d(33) of 2-2 composites with the magnetic field heat treatment have been improved, compared with that without magnetic field heat treatment. The maximum value of d(33) of the sample with magnetic field heat treatment is 71% larger than that without magnetic field heat treatment. (C) 2007 Elsevier B.V. All rights reserved.