Hot Workability and Processing Map of Ultrafine-Grained Al/SiC Composite with Different Reinforcement Sizes Under Compressive and Tensile Modes

The thermo-mechanical properties of severely deformed ultrafine-grained aluminum composites are extremely important for successful forming in various components under hot-forming conditions. Since the size of reinforcement particles plays a vital role in the forming of composites, the current work was designed to study the hot workability of ultrafine-grained (UFG) AA6063-SiC composite with different sizes of reinforcements [coarse (12 µm), fine (1 µm) and nano (45 nm)]. The optimum processing parameters for the successful forming of UFG composites were derived with processing maps obtained by conducting hot tension and compression tests at different temperatures from 300 °C to 450 °C and at strain rates between 0.001 to 10 s⁻¹. Microstructural observations showed dynamic recrystallization as the dominant deformation mechanism in the stable zones in both tension and compression, while the unstable zones showed an uneven microstructure and microcracks. The activation energy for hot deformation decreased with decreasing particle size. The relationship between kinetic analysis and processing maps was established and interrelated based on their microstructures. The work carried out in the present study provides, for the first time, a quantitative analysis for hot deformation of these UFG composites with varying reinforcement sizes in both tension and compression.