Elastic properties of sphere-reinforced composites with a mesophase

The elastic properties of a three-phase composite made up of spherical particles coated with a mesophase and dispersed in a continuum matrix were computed through a periodic microfield approach. The composite was idealized as a three-dimensional array of either aligned or staggered hexagonal prisms, each containing one coated particle at the center. While the response of the aligned distribution was too stiff, the results obtained for the staggered arrangement were in good agreement with experimental data and with the predictions of the classical mean-field models for two-phase composites. The model was then used to explore the effect of a mesophase in the elastic modulus of a material with a large mismatch between reinforcement and matrix stiffness (E-r/E-m = 1000). A significant variation in the elastic modulus was found for a sphere radius to mesophase thickness ratio below 10 when the mesophase elastic modulus was comprised between those of the matrix and of the reinforcement. The model predictions of this behavior were in agreement with experimental data found in the literature. (C) 2000 Acta Metallurgica Inc. Published by Elsevier Science Lid. All rights reserved.