Elastic behaviour of a model two-phase material

Dense Al2O3–NiAl composites containing 0–100% NiAl were prepared in the present study, and their elastic properties are determined by a dynamic method. Comparisons are made between the experimental data and several theoretical models. The elastic and shear moduli fall within the Voigt–Reuss bounds and close to the lower bound of the Hashin–Shtrikman (H–S) model. Nevertheless, the bulk modulus and Poisson’s ratio of the composites show strong dependence on their microstructural characteristics. As two phases are interconnected in the composites to form an interpenetrating microstructure, the bulk modulus deviates considerably from the Voigt–Reuss and H–S bounds. However, the Poisson’s ratio of the composites containing only one continuous phase differs from the model predictions.