Microstructure Evolution and Mechanical Properties at Ambient and Elevated Temperatures of in-situ TiB2/2219Al Matrix Composites During Cold Rolling

Cold rolling is one of the feasible and effective methods for regulating the microstructure and enhancing the mechanical properties of metallic materials. However, the cold rolling of particulate-reinforced aluminum matrix composites has been rarely studied comprehensively and systematically due to their limited plasticity. In this study, in-situ TiB₂/2219Al matrix composites with a comparable ductility to 2219Al matrix were prepared and subjected to T3 treatment, which includes solution treatment, cold rolling, and natural ageing, with varying degrees of rolling reduction. The effects of cold rolling on the dislocation multiplication, grain and texture evolution, precipitation behavior, and mechanical properties were comprehensively investigated and discussed. The results reveal that both total dislocation density and geometrically necessary dislocation density increase with increasing rolling reduction. The average grain size progressively decreases under the joint influence of gradual growth of large grains and increase of small grains. Besides, rolling deformation changes the ageing behavior of composites, resulting in a decrease in precipitation temperature for both θ″ and θ′ phases. Under a large deformation, these phases precipitate at room temperature. Moreover, the types and proportions of textures undergoes a distinct evolution during deformation, with S, Copper and Brass textures being predominantly observed in the composite subjected to a 60% rolling reduction. Additionally, the increase in deformation results in an enhanced hardness and strength at both room temperature and 373 K. However, the strength initially increases but subsequently decreases at 573 K, and the composite with a 20% rolling reduction exhibits the highest strength at 573 K.

Graphical Abstract