Formation of nanoporous Ta structure on Ti-Ta alloy based on a novel surface dealloying process

Nanoporous metals are considered as functional materials of great research significance that can be widely used in energy storage, sensing, catalysis and so on. However, the research on nanoporous refractory metal structures is limited, commonly used liquid metal dealloying (LMD) often requires the reaction temperature to reach the melting point of the solvent metal that used as the dissolution medium and the reaction time is normally very short, resulting in a low controllability of the structure size. In the present study, we have developed a novel surface dealloying (SD) process to prepare nanoporous Ta structures directly generated on the surface of Ti-Ta alloys. Porous Ta structures with average ligament sizes of 226-733 nm were obtained by tuning the annealing process parameters. Compared with the conventional metal dealloying process, the SD process could produce a nanoporous surface layer with fine structure and more tunable size characteristic. In addition, we explored the effect of annealing temperature on the dealloying mechanism and found that the dealloying was likely underwent transient liquid phase (TLP) dealloying process during the annealing at 900°C.