Magnetomechanical coupling and elastic moduli of polymer-bonded Terfenol composites

The dependence of coupling coefficient (k) and elastic moduli (E-H and E-B) on particle size and volume fraction of Terfenol powder in polymer-bonded composites has been investigated. Materials were prepared with powder in five size ranges between 106 and 710 mu m and in three volume fractions (V-F) The moduli show a Delta E effect, which is negative for small bias fields and positive for larger fields. E-H is found to be independent of particle size and to vary with V-F in agreement with model predictions. The maximum value of k, for each sample, is found to be independent of both particle size and V-F and a simple model is presented which predicts this behavior and indicates that the low values of k(max) arise mainly from the low modulus of the epoxy binder. (C) 1998 American Institute of Physics. [S0021-8979(98)25311-4].