Investigation into the effects of varied pressure application techniques on microstructural evolution and thermal conductivity of SiCp/Al composites manufactured via stir casting

The elimination of defects is critical for enhancing microstructural uniformity and thermal conductivity of Al composites prepared by stir casting. External pressure enhances the densification of composites. Exploring its influence on microstructural and thermal conductivity evolution during defect healing is of both engineering and theoretical significance. This study prepared 16SiC p /Al composites via stir casting to evaluate the effects of hot pressing(HP) and hot isostatic pressing(HIP) on the microstructure, mechanical properties, and thermal conductivity of Al composites. HP decreased the area fraction of hole defects from 14.54% to 1.24%, with the reduced interfacial gaps between SiC p and the matrix alloy significantly improving the composites tensile strength from 33 MPa to 150 MPa and decreasing the total interfacial thermal resistance. The free electron and phonon scattering effect was weakened and the heat flow transfer path was shortened, increasing the thermal conductivity of the composites from 98.5 to 125.9 . HIP reduced the area fraction of hole defects to 0.58%. The Al matrix reacts with the nickel-plated surfaces of the SiC p to form the Al 3 Ni phase. HIP causing spheroidization of eutectic Si with the fragmented Al 3 Ni phase transforming from blocky and skeletal to short strip and blocky. The refinement of the eutectic Si and the Al 3 Ni phase morphology reduced the obstacles to heat flow, increasing the mean free path of free electrons and phonons, thereby enhancing their mobility with the tensile strength and thermal conductivity of the composites reaching 193 MPa and 159.5 , respectively. This study provides theoretical guidance for the fabrication of high-strength and high-thermal-conductivity Al composites.