Recent advances in multimaterial structural architectures focus on integrating distinct mechanical and thermal properties within a single element. This study investigates the simultaneous enhancement of thermal conductivity and compressive yield strength in multimaterial core–shell extruded rods fabricated from Al-alloy/17.5 vol% SiC composites, Al-Si-Mg alloys, and Cu across various configurations. Both conventional cylindrical and novel cup–cone billet geometries were evaluated to modulate material flow and control the resulting core–shell architecture. Microstructural characterization confirmed continuous core–shell structures in selected configurations with systematically varying shell thicknesses and strong metallurgical bonding at the core–shell interfaces. For Cu-containing configurations, interfacial integrity heavily depended on the specific arrangement and flow-stress mismatch. The cup–cone geometry promoted more stable and continuous core–shell formation by accommodating differential material flow during co-extrusion. Along the extrusion direction, the cup–cone Al6063-core and Al6063/SiC-shell configuration increased thermal conductivity by 5.63% over monolithic Al6063 and 7.86% over the Al6063/SiC composite, while simultaneously enhancing compressive yield strength by 50.8% over monolithic Al6063. Furthermore, the Cu-core with Al6063/SiC-shell architecture (cup–cone) achieved a thermal conductivity of approximately 350 W/mK and a compressive yield strength of 341.9 MPa, corresponding to approximately 87.5% of the conductivity of bulk Cu while retaining exceptional load-bearing capability. This unusual performance arises from spatially partitioning thermal and mechanical functions: the continuous Cu core provides a highly conductive heat-transfer pathway, whereas the strengthened Al/SiC shell sustains mechanical loads. Consequently, these tailored core–shell architectures successfully push beyond the conventional strength–thermal-conductivity trade-off envelope.
