Particle distribution study for low-volume fraction magnetostrictive composites

We present experimental results for [1-3] magnetostrictive composites conta ining a 20% volume-fraction of Terfenol-D coarse particles (>>1 mum) suspen ded in a nonmetallic binder. Results from magnetostrictive strain and magne toelastic measurements are provided for particle distributions that differ in particle size and range of size distribution. Particle size and packing density are shown to effect strain response and are attributed to demagneti zation and loading (prestress) effects. Both a decreasing and increasing De ltaE effect are measured for low and high fields, respectively, and found t o be independent of particle distribution. The response of an optimized bim odal distribution increases packing density and produces 15% larger magneto strictive strains than the other widely dispersed (polydispersed) (< 106, < 212, and < 300 mum) and narrowly dispersed (monodispersed) (< 45, 98, and 275 mum) distributions at comparable magnetic field levels. (C) 2001 Americ an Institute of Physics.