Constructal Design and Friction Stir Processing Synergy: Towards Next-Generation High-Efficiency Heat Sinks

The continuous increase in electronic power densities demands thermal management solutions that surpass the conventional heat sink designs. This study introduces a synergistic approach that combines constructal design principles with Friction Stir Processing (FSP) to create next-generation heat sinks featuring an optimized geometry and locally enhanced thermal conductivity. Constructal design provides a physics-based framework for routing heat through preferential paths, whereas FSP enables the fabrication of these paths by refining the microstructure and reducing defect density, thereby improving thermal transport properties. Experimental validation on the AA6082-T651 aluminum alloy demonstrated a 21% increase in thermal conductivity within the FSP-processed regions, as confirmed through electrical resistivity measurements and thermal step-response tests. Microstructural analysis revealed significant grain refinement (from ~150 μm to 3–5 μm), which correlated with enhanced heat diffusion rates. A constructal scale-based model was developed to establish the relationship between the conductivity ratio and optimal geometric configuration, showing that a higher local conductivity shifts the design toward denser thermal pathways. These findings substantiate the feasibility of integrating geometry optimization with property tailoring, paving the way for scalable, high-efficiency heat sinks for advanced cooling systems.