Dealloying behavior of amorphous binary Ti-Cu alloys in hydrofluoric acid solutions at various temperatures

A nanoporous copper structure was fabricated from amorphous binary TixCu_100-x (x = 40, 50 and 60 at.%) alloys in hydrofluoric acid solutions under a free corrosion condition. A bi-continuous nanoporous structure has a pore size of 25-75 nm and a ligament size of 46-79 nm in 0.03 M HF solution. In 0.13 M HF solution, a pore size of 85-380 nm and a ligament size of 80-338 nm were obtained. The dealloying process is thermal-activated and obeys the Arrhenius law. The surface diffusivity decreases with temperature and concentrations of dealloying solutions. The values of the activation energy of copper adatoms are estimated to be 40.3-78.1 kJ mol^-1, which depend not only on the alloy composition but also on the dealloying electrolyte composition.