According to the problems in coarse primary silicon and acicular eutectic silicon in traditional hypereutectic Al-Si alloy

the semi-solid slurry of Al-28 Si alloy was prepared by serpentine channel composite Sr modification process. The microstructure of the semi-solid slurry and the precipitation temperature of primary silicon were investigated. The results reveal that the composite process can fully refine the primary silicon and effectively modify the eutectic silicon. The primary silicon is refined from 165.26 μm to 45.68 μm

and the structure of eutectic silicon is transformed from acicular to punctate and worm-like. With the increase of the Sr addition

the precipitation temperature of primary silicon is increased at first and then decreased

and the grain size shows an increasing trend. The growth of eutectic silicon with a large number of fibrous branches is limited by aluminum phase.