Study on the Effect of Micromorphology and Creep Properties of In Situ (ZrB₂ + Al₂O₃)/AA6016 Composites in Extruded State

This research was designed to synthesize in situ double particles (Al₂O₃ + ZrB₂)/6016Al composites using a 6016Al-Na₂B₄O₇-K₂ZrF₆ in situ reaction system. The effects of particle content and extrusion deformation on the microstructure and high temperature creep resistance of the composites were studied, and the strengthening mechanism and creep resistance mechanism were analyzed. The conclusions are as follows: The addition of double reinforcing particles (Al₂O₃ + ZrB₂) increased grain boundaries, the transformation of grains to equiaxial crystals, and refined grain size. When the content of reinforcing particles is too high, the reinforcing particle clusters are severe, weakening the fine crystallization effect. The extruded composite grains are fibrillated, and the reinforcing particle clusters are elongated and tend to be dispersed. When the content of reinforcing particles is elevated, the duration of the steady-state creep process increases, and the steady-state creep rate decreases, which is also much lower than that of the base alloy. Under the same temperature and stress conditions, the three creep parameters of apparent stress index n_a, apparent activation energy Q_a, and threshold stress σ_th increase with the increase in reinforcing particle content. This study discusses the mechanism of particle content on the high-temperature creep properties of extruded-state aluminum matrix composites, which provides new perspectives and guidance for the design and fabrication of composites with superior high-temperature creep properties.