Influence of microstructural features on the effective magnetostriction ofcomposite materials

Recently developed magnetostrictive composites of a giant magnetostrictive alloy and an inactive matrix have opened up a promising territory for the a pplication of materials with magnetic-mechanical coupling interactions. In this article an effective-medium method is developed for the effective magn etostrictive behavior of such composite materials based on a Green's-functi on technique. Explicit relations for determining the effective magnetostric tion of the spherical particulate and fibrous composites with elastically i sotropic magnetostrictive crystallites are derived. Two extreme bounds-the Reuss and Voigt-type bounds-are also given. To illustrate the technique, nu merical calculations for the effective saturation magnetostriction of SmFe2 /epoxy or aluminum and Terfenol-D/epoxy or aluminum composites with various phase compositions, particle shapes and orientation, and crystallite growt h directions, are performed. The theoretical estimates are found to be in a greement with available experimental results, and they also show the intere sting magnetostrictive behavior of the composites. [S0163-1829(99)01933-5].