Enhancing the inner heterogeneous surface functionality of laser powder bed fused W-Cu minichannels by combining abrasive flow machining and electroless nickel deposition

To develop advanced materials for high-efficiency heat sinks, W-Cu composites with a circular minichannel structure were fabricated via laser powder bed fusion (LPBF). A gradient W phase distribution was observed across the minichannel cross-section, with the near-surface region consisting predominantly of discrete W particles, whereas a continuous skeletal W structure formed in the interior. Owing to intrinsic LPBF defects such as adhesive particles and staircase effects, the as-built minichannel surfaces exhibited high roughness (∼11.38 μm) and a significant roundness error (∼159.5 μm), which would adversely affect fluid flow and heat-transfer efficiency. Consequently, abrasive flow machining (AFM) treatment was employed to improve the inner surface quality of the minichannel. Under the optimal AFM conditions (10 MPa pressure, 2000 cycles, 15 μm abrasive), the surface roughness and roundness error were reduced to 2.18 μm and 38.2 μm, respectively. This process simultaneously removed the surface W particle region and exposed the smooth skeletal W structure beneath. To meet the requirement for corrosion resistance in service, a uniform and dense Ni-P plating was subsequently deposited on the inner surface of the AFM-treated minichannel via electroless deposition (ED). Electrochemical tests demonstrated that the plating could significantly reduce the corrosion current density and enhance corrosion resistance. The present synergistic strategy of surface morphology control and protective plating deposition markedly improved the functionality of the W-Cu minichannels, providing a foundation for developing high-performance, durable thermal management components.