Fabrication and structure evolution of porous copper via one-step dealloying of H62 copper-zinc alloy

Abstract

Porous copper with adjustable structures was successfully prepared from a low-cost H62 Cu-Zn alloy using one-step chemical/electrochemical dealloying method. The effects of dealloying conditions on the porous microstructure and dealloying mechanism were investigated. The results show that during chemical dealloying, the dealloying mechanism remains constant, involving only atomic diffusion and dissolution. This leads to a consistent bicontinuous porous structure across all chemical dealloying conditions. In contrast, applying additional potentials not only accelerates the atomic diffusion and dissolution, but also shifts the dealloying mechanism from asynchronous corrosion to galvanic corrosion, and forms various porous structures. Notably, hierarchical porous Cu is only fabricated by precisely controlling the dealloying potential at intermediate levels around 0.2 V. The finally dealloying morphology arises from the competition between diffusion and dissolution, and similar porous morphologies are achieved by keeping D_s at comparable levels. The nano-hardness and elasticity modulus of all dealloyed H62 alloys are reduced depending on their structure. However, the prepared bimodal porous Cu exhibits a higher nano-hardness of 0.28 ± 0.04 GPa compared to most reported porous metals, which is beneficial for its service performance and lifespan.