Aluminium matrix composites by pressureless infiltration: the metallurgical and physical properties

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 X 106 and 7 X 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.