Abstract: Impact property of 2A14 aluminum alloy after solution and aging treatment was studied by means of SEM and impact testing machine. The results show that the second phase existing in the as-casted specimen is mainly composed of AlCuMgSi phase particles with thin strip morphology. There is also a small amount of circular Al₂Cu phase in the grain. The strip-shaped AlCuMgSi phase particles have a high aspect ratio, which is brittle and easy to break from the middle of the particles when plastic deformation occurs, which cannot effectively improve the material impact property. The core of the short rod-like AlCuMgSi phase after solution and aging treatment contains more Fe and Cu with higher melting temperature, which improves the thermal stability of the second phase particles. With the process of aging, the second phase particles grow up with heat-resistant phase as its core, and evolve into short rod-like finally. After solution and aging treatment, the original reticulated second phase remelts into the matrix and transforms into a more stable short rod-like precipitate, which can absorb more impact loads. At the same time, the fine Al₂Cu phase in the grain also grows significantly. The dispersed precipitated phase particles can better coordinate the plastic deformation and further improve the impact property.

Key words: 2A14 aluminum alloy, solution and aging treatment, impact property, second phase particles, heat-resistant phase