Microstructure and elastic-constant measurements of two-phase materials

Considering two-phase materials, we focus on the relationship between microstructure and physical properties, especially elastic constants. Microstructure includes occlusion concentration, orientation, shape, size, and distribution. Isotropic materials possess two independent elastic constants; orthotropic materials, nine; we emphasize the need to determine the complete elastic-constant tensor. We review principally three measurement methods: pulse-echo, rod-resonance, and acoustic-resonance spectroscopy. We show results for SiC_p/Al, mullite_p/Al, graphite_p/ferrite (cast iron), voids/Ti, B_f/Al, graphite_f/Al, SiC_sf/Al, epoxy/Al laminate. For some cases, we show the elastic constant´s imaginary part: attenuation or internal friction. We emphasize combining measurements with modeling