Structure and mechanical properties of Al-based gradient composites reinforced with primary Si and Mg2Si particles through centrifugal casting

The structure and mechanical properties of a new type of Al-based discontinuous gradient composites prepared by using the ternary Al-19Si-5Mg alloys as the raw material adopting the centrifugal casting method were investigated. Structurally, the composites are divided into two zones: a reinforced zone with the high volume fraction of primary Si and Mg₂Si particles and an unreinforced zone with no or a few particles. In the reinforced zone, the primary particles are evenly distributed, with the sizes of the primary Si particles 80–120 μm, and that of primary Mg₂Si particles 20–50 μm. The properties test results show the reinforced zone has higher Rockwell hardness and better wear resistance than the unreinforced zone, due to the complementary reinforcement relationship between the primary Si and Mg₂Si particles and their high volume fraction.