Laser Powder Bed Fusion of a Hypereutectic Al-Cu Alloy and Its Application to the Development of a Hierarchical Porous Cu with Controllable Three-Scale Hierarchy

Hierarchical nanoporous metals have nanometer-scale pores on the surface of a larger-scale structure. The hierarchy of the porous structure combines both a high specific surface area and good fluid permeability, enhancing catalytic performance. In this study, laser powder bed fusion (L-PBF) of a hypereutectic Al-Cu alloy is explored as a route to manufacture hierarchical nanoporous Cu. The L-PBF process enables the fabrication of the lattice structure, and the subsequent dealloying process imparts nanometer-scale pores on the surface of the lattice structure (nano/millimeter-scale hierarchy). In addition, rapid solidification in the L-PBF process introduces a refined microstructure with high interfacial energy, enabling the control of microstructural morphology through annealing. Dealloying from the annealed microstructures enables the formation of micrometer-scale pores, on which the nanometer-scale pores are formed. As a result, the microstructure of the L-PBF-processed Al-27 mol%Cu alloy was controlled through annealing, and subsequent dealloying formed a nano/micrometer-scale hierarchical porous structure not only on its cross-section but also on its surface. This study provides a novel process concept for manufacturing hierarchical nanoporous metals with nano/micro/millimeter-scale hierarchy.