Strengthening mechanism induced by the solid-to-semisolid hot isostatic pressing of 55 vol.% SiCp/6061Al composites

The near-net shape formation of high-volume fraction SiCp/Al composites via semi-solid hot isostatic pressing (HIP) was proposed as a potential solution to the challenges posed by the integration of the composite preparation and processing. The effects of the HIP process with solid-state holding followed by semi-solid heating, hereafter referred to as the solid-to-semisolid HIP (S-SS HIP) process on the microstructure and mechanical properties of the composite were investigated. The formation of the α-(AlSiMnFe) phase was observed in the composites produced by semi-solid HIP, and the MgAl₂O₄ phase precipitated at the interface between the SIC and 6061Al. The S-SS HIP process facilitated strain-energy storage and the formation of subgrains in the matrix. After T6 heat treatment, the average grain size of the S-SS HIP-T6 sample was significantly reduced. The UTS of the S-SS HIP-T6 sample increased by 5.1%, reaching 517.7 MPa, compared with the HIP-T6 sample produced without the S-SS HIP step.