Fabrication of nanoporous copper by dealloying of amorphous Ti-Cu-Ag alloys

Ternary TiCuAg amorphous alloys were used as the starting materials for fabricating nanoporous copper (NPC) in HF solutions. NPC with a pore size of 8-55 nm was fabricated through dealloying from an amorphous Ti60Cu40-xAgx (x = 1, 2 at.%) ribbon alloy under free immersion conditions. A 3-dimensional bicontinuous NPC structure formed on Ti60Cu40, Ti60Cu39Ag1, and Ti60Cu38Ag2 ribbon alloys with pore sizes of 130 nm, 48 nm, and 55 nm, respectively, after immersion in 0.13 M HF solution for 43.2 ks. The pore sizes of dealloyed ribbon alloys in 0.03 M HF solution were confirmed to be 71 nm, 41 nm and 39 nm, respectively. The pore size of NPCs dealloyed from Ag-added alloys was smaller than that of the Ti-Cu alloy. Smaller pores formed in the beginning of dealloying because even distributed Ag atoms in amorphous precursors suppressed the diffusion of Cu adatoms. The final characteristic pore size showed a weak dependence on the solution concentrations. Diffusivity decreased more than two orders due to the alloying of Ag. The dealloying residue was fcc Cu-Ag and Ag, with Ag adatoms concentrated at the grain boundary. The uneven distribution of Ag atoms caused the coarsening of nanoporous Cu after the prolonged dealloying. (C) 2013 Elsevier B. V. All rights reserved.