Solution treatment: A route towards enhancing tensile ductility of SiCp/6061Al composite via powder thixoforming and comparison of micromechanical strength modeling

In this study, SiC particles (SiCp) with a mean size of 6.94 µm were well dispersed in the 10 vol% SiCp/6061Al composite prepared by powder thixoforming that combines the merits of powder metallurgy and thixoforming. The composites had evidently strengthened tensile strength while possessed a low elongation. However, a tailored solution treatment at 560 °C for 6 h can compensate the ductility loss to a large degree (169.2% increment in elongation as compared to the as-fabricated composite) besides an acceptable increment in tensile strength (20% and 67.2% increments in ultimate tensile strength and yield strength, respectively), due mainly to the improved ductile matrix and the enhanced interfacial bonding strength resulting from the disappearance of eutectic phases. According to the comparison results of the existing micromechanical strengthening models, the strength increments resulting from load transfer mechanism and solid solution strengthening contributed most to the yield strength, revealing the significance of SiCp addition and solution treatment. However, the strengthening efficiency of SiCp was largely affected by their failure fraction during tensile test and the model that was previously proposed by the authors had a better agreement with the experimental results than the other models. These results not only provided a pathway to achieve high strength SiCp/6061Al composites with enhanced ductility, but also shed light on a more reasonable model for the strength prediction of solutionized composites.