Effects of Microstructure on Mechanical Properties of Hyper Eutectic Al-Si Alloy Produced by Spark Plasma Sintering

A hyper eutectic Al-24mass%Si alloy powder atomized in Ar was consolidated by spark plasma sintering (SPS) and the effect of the microstructure on mechanical properties of the sintered compact was examined. The sintered compact produced by SPS method at a sintering temperature of 723 K which is 150 K lower than that of PM method was fully densified, and had good mechanical properties. When the Al-24mass% alloy powder was consolidated by SPS, the microstructure became a morphology which proeutectic Si regularly arranged at the boundary between the powder particles. This result indicates the occurrence of the local melting on the powder surface. Consequently, the stable oxide film on the powder particle surface was removed by occurrence of spark plasma during SPS and the strong bonding between the particles was obtained.