Giant Reversible Magnetostriction in a Ferromagnet–Polymer Composite.

A magnetostrictive ferromagnet–polymer composite consisting of steel wires suspended in a polymer matrix has been developed that exhibits large reversible magnetostrictive strain in relatively low magnetic fields. The strain for a fixed field is a nonmonotonic function of wire loading for the longer wires investigated, and the strain for a given wire loading increases with decreasing the wire length. Within the limits of this study, a maximum saturation strain of 60.2% in a 7.5 kOe field was observed with a wire length of 0.50 cm and a wire volume fraction of approximately 0.2. No degradation in strain was observed over the maximum number of 50 expansion cycles.