Influence of processing routes and SiC volume percentage on microstructure, thermophysical, and mechanical properties of SiCp/Al-6061 composites

SiCp/Al are considered promising candidates for structural and thermal applications, but their performance is highly dependent on fabrication routes and interfacial characteristics. In this study, SiCp/Al composites containing 10–70vol% SiC were fabricated using two distinct powder metallurgy approaches: V-blender and hot press sintering and ball milling and hot press sintering. At 30 vol%, the V-blended composites attained a tensile strength of 286.2 MPa, flexural strength of 540.2 MPa, compressive strength of 882.5 MPa, and thermal conductivity of 187.8 W/m.K. The ball-milled composites achieved higher values at the same reinforcement level, with a tensile strength of 369.6 MPa, flexural strength of 620.6 MPa, compressive strength of 909.5 MPa, and thermal conductivity of 193.6 W/m.K. TEM analysis revealed semi-coherent Al(111)/SiC(102) interface with visible dislocation tangles. While Williamson-Hall analysis confirmed a high dislocation density (∼3.27 × 10 ¹⁴ m^-²) in the ball-milled samples, consistent with their superior thermophysical and mechanical performance. In both processing routes, performance declined at higher SiC contents due to increasing porosity, which reached about 20–22 % at 70 vol%. These findings demonstrate that the thermophysical and mechanical response is strongly controlled by microstructural features, particularly interface state, dislocation density, and porosity. Ball milling offers the best balance of mechanical and thermal properties at 30–40 vol% SiC, while V-blending provides good performance with simpler processing up to about 30 vol%. A critical porosity threshold of ∼10 % was identified, above which mechanical and thermal properties deteriorated regardless of SiC content, establishing porosity as a dominant performance-limiting factor.