Dependency of the formation of Au-stabilized nanoporous copper on the dealloying temperature

Au-stabilized nanoporous Cu with a pore size of 7-24 nm was fabricated through the dealloying of amorphous Ti₆₀Cu_{40- x}Au_x alloys (x = 1, 2 at%) in HF solutions at 298, 323 and 348 K. Nanoporous structures with larger sizes of bi-continuous pore-to-ligament were obtained at higher temperatures. The residue was confirmed to be crystalline fcc Au and a Cu-Au solid solution. The surface diffusivity of Cu adatoms decreased more than 4 orders of magnitude due to the involvement of Au atoms as the temperature decreased. The surface diffusivity had a linear dependence on the reciprocal of the temperature, in accordance with the Arrhenius law. The activation energy of surface diffusion for amorphous TiCuAu alloys was estimated to be 56.1-62.7 kJ mol^-1, which was independent of the Au content and the concentration of the HF solutions.