Abstract: Impact properties of the ZL108 aluminum alloy after solution aging treatment were studied by means of OM, SEM and impact testing machine. The results show that the as-cast microstructure is mainly composed of α solid solution, coarse eutectic silicon and bulk primary silicon. After solution and aging treatment, the precipitated phase is fine and evenly distributed, with a morphology similar to short rod or coral shaped, which can better pin dislocations and help improve the impact properties of the material. The non-equilibrium distribution of elements in the as-cast specimens results in the production of a large amount of refractory eutectic silicon and bulk primary silicon. After solution and aging treatment, the precipitated phase particles continue to break under high temperature, and most of them are remelted into the matrix. The remaining precipitate particles have smaller sizes, which can better coordinate the deformation of the matrix and improve the impact properties of the specimen by 6.6 times.

Key words: solution and aging treatment, eutectic silicon, impact properties, precipitated phase particles