Aluminum alloy matrix composites have emerged as candidate materials for electronic packaging applications in the field of aerospace semiconductor electronics. Composites prepared by the pressureless infiltration technique with high volume fractions in the range 0.41–0.70 were studied using ultrasonic velocity measurements. For different volume fractions of SiC, the longitudinal velocity and shear velocity were found to be in the range of 7600–9300 m s−1 and 4400–5500 m s−1, respectively. The elastic moduli of the composites were determined from ultrasonic velocities and were analysed as a function of the volume fraction of the reinforcement. The observed variation is discussed in the context of existing theoretical models for the effective elastic moduli of two-phase systems.

Aluminium matrix composites containing a high volume fraction of silicon carbide particulates were produced by the pressureless infiltration technique. The metal matrix composites thus obtained were characterized for phase composition, microstructure, density, porosity and coefficients of thermal expansion. All composites were studied in their as-prepared condition without any further heat treatment. Behaviour of bulk properties such as thermal expansion and density was studied as a function of the volume fraction of silicon carbide within the volume fraction range 0.41–0.67. The coefficients of thermal expansion of the composites were found to vary between 14 × 10−6 and 7 × 10−6 K−1 in a non-linear fashion as a function of the volume fraction of SiC. The variation in the density of the composites was found to be linear with volume fraction in the usual manner. The results obtained were compared with existing models on the behaviour of macroscopic properties of composite materials