Effects of melt mixing and AlTi5BRE10 inter alloy on solidification of microstructure of hypereutectic Al–Si alloy

Abstract

The solidification of microstructure of hypereutectic Al-20%Si alloy obtained by mixing high-temperature Al-30%Si alloy melt and low-temperature Al-10%Si alloy melt in a mixing ratio of 1 : 1 was investigated by optical microscopy. A certain amount of AlTi5BRE10 inter alloy was added into high-temperature Al-30%Si alloy melt before mixing. The results showed that the primary Si crystals were refined and passivated by the melt mixing process and a certain amount of AlTi5BRE10 inter alloy further refined the primary silicon and α-Al phase. The coarse plates, petals and irregular triangular-shaped primary Si crystals turned into fine block shapes, and the α-Al phases were spherical. After the melt mixing treatment, the microstructure of the hypereutectic Al-20%Si alloy was composed of a primary α-Al phase, eutectic (α + Si) phase, and the primary silicon, which caused the hypereutectic Al-20%Si alloy to exhibit typical hypoeutectic and hypereutectic characteristics.