Use of Lightweight Metal-Matrix Composites for Transportation Applications in India

Aluminum alloy (A359) - fly ash composite ingots and selected parts were successfully cast in sand and permanent molds using conventional foundry techniques from large scale heat (400 pounds). The sand, permanent mold, and squeeze castings including intake manifolds, brake drums, motor mount, and mounting bracket, show adequate castability of the melts containing fly ash particles. The results of microstructure analysis and property examination indicate that the strength of casting is significantly influenced by the amount and distribution of fly ash particles in castings. The room temperature tensile strength of composite castings containing less than 8 vol.% fly ash is similar to that of the base alloy, and then decreases with further increase in fly ash contents. This decrease in properties may be related to clusters of fly ash observed in the microstructures of castings; work is in progress to improve the distribution of fly ash in the matrix and enhance its bonding with the matrix. The tensile strength measured at 600 °F is about 7 to 10 ksi for the composite castings containing 2 to 12 vol.% fly ash which is higher than that of the base alloy (4 ksi).