A new method for continuous casting of particulate reinforced metal matrix composite wires

The horizontal Ohno continuous casting (OCC) process has been used to examine the possibility of casting net-shape metal matrix composite (MMC) wires, ∼2 mm in diameter. The foundry alloy, Al-7%Si-0.4%Mg (A356) containing ∼ 11 vol.%SiC particles was used for this study. It was confirmed for the first time that net-shape MMC wires with relatively uniform particle distribution could in fact be produced by the OCC process. At lower casting speeds (0.15-0.2 m min−1), an external force, induced by impeller stirring in the mould cavity, was necessary in order to assist particle flow into the narrow mould channel and thus ensure incorporation of particles within the wires. At higher casting speeds of about 1 m min−1, particles were incorporated without external force. It was observed that the distribution of particles within the matrix was independent of the refinement of the microstructure when the dendrite arm spacing was smaller than the particle size.