Elaboration of nanoporous copper by modifying surface diffusivity by the minor addition of gold

The basic concept of alloying was combined with modifications of the surface diffusivity through the addition of trace metals with low surface diffusivity in order to elaborate the dealloyed nanoporous metals. Nanoporous Cu with a pore size less than 10 nm was able to be elaborated. This nanoporous Cu was fabricated through dealloying from amorphous Ti ₆₀Cu _40-xAu _x (x = 0, 1, 2 at.%) ribbon alloys under free immersion conditions. A bicontinuous nanoporous Cu structure formed on Ti ₆₀Cu ₄₀, Ti ₆₀Cu ₃₉Au ₁, and Ti ₆₀Cu ₃₈Au ₂ ribbon alloys with pore sizes of 140, 19, and 9 nm, respectively, in 0.13 M HF solution. The pore size of the nanoporous Cu dealloyed from Au-added alloys was more than one order smaller than that of the Ti-Cu alloy. The pore size depended not only on the treatment solutions and treatment time but also on the alloy compositions. The uniform distribution of an Au additive on Cu in effect modified the surface diffusivity, resulting in the formation of an ultrafine nanoporous structure. The surface diffusivity was estimated to decrease from 2.49 × 10 ^-17 to 5.88 × 10 ^-22 m ² s ^-1 by adding 2 at.% Au to Ti ₆₀Cu ₄₀ ribbons.