Nickel-stabilized nanoporous copper fabricated from ternary TiCuNi amorphous alloys

Minor additive nickel (1 at%) to Ti–Cu amorphous alloy helped to form the finer nanoporous copper (NPC). The pore size of open-cell nanoporous fcc Cu was confirmed to be 71 nm for Ti60Cu40 alloy and 23 nm for Ti60Cu39Ni1 alloy after immersion of 43.2 ks in 0.03 M HF solution at 298 K. The pore size increased with immersion time in a form of the power law function with an exponent of 0.26. The estimated surface diffusivity decreased by about two orders of magnitude from 2.5×10−18 to 2.7×10−20 m2 s−1by adding 1 at% Ni to Ti60Cu40 ribbons. The activation energy of surface diffusion of Cu atoms was estimated to be 68 kJ mol−1. The refinement of nanoporous Cu was resulted from the additive Ni with one-order lower surface diffusivity than Cu. Ni adatoms acted as a barrier for the diffusion and rearrangement of Cu adatoms, as a result, the smaller nanopores formed on Ti–Cu–Ni amorphous alloy.

► Fine nanoporous Cu was fabricated from ternary TiCuNi amorphous alloy.
► Ni addition was effective for refining nanoporous Cu.
► Ni addition decreased the surface diffusivity about two orders.
► Ni adatoms suppressed the Cu diffusion during dealloying and re-arrangements.