Microstructures, mechanical properties, and aging behavior of hybrid-sized TiB2 particulate-reinforced 2219 aluminum matrix composites

Particulate-reinforced aluminum matrix composites are widely used owing to their advantageous comprehensive performance. For these composites, aging treatment is an important and essential process. However, researchers have discrepant opinions regarding the exact effects of particles on the aging behavior. In this study, the aging behavior of TiB2/2219Al composites is analyzed in terms of thermodynamics and kinetics. The results reveal that the particles can both promote aging and impede aging, and the peak aging times of the composites are advanced in this study. The effects of hybrid-sized TiB2 particles on the microstructures and mechanical properties of aged TiB2/2219Al composites are investigated. The results show noticeable dislocation propagation after the addition of TiB2, and this is confirmed by transmission electron microscopy observations and modified Williamson–Hall equation calculations. The Vickers hardness values are increased under all aging conditions. The strengths of the naturally aged composite, yield strength of the under-aged composite, and Young's modulus are increased significantly, whereas the strengths of composites under other aging conditions record only slight improvement. The total elongations of all the composites are decreased owing to the presence of TiB2 agglomerates.