Structure analysis of precursor alloy and diffusion during dealloying of Ag–Al alloy

Nanoporous silver (NPS) was fabricated by dealloying Ag–Al alloy ribbons with nominal compositions of 30, 35 and 40 at% Ag (corresponding to hypoeutectic composition, eutectic composition and hypereutectic composition, respectively). The microstructures of the Ag–Al precursor and as-dealloyed samples were observed using a scanning electron microscope (SEM) and a transmission electron microscope (TEM) as well as via focused ion beam (FIB) technique. We concluded that with the increase in Ag content from 30 to 40 at%, the diameter of ligament increased from 70 ± 15 nm to 115 ± 35 nm. Due to the method of crystalline solidification and the distribution of α-Al(Ag) and γ-Ag(2)Al phases, the as-dealloyed Ag(35)Al(65) alloy exhibited a homogeneous ligament/pore structure, whereas the microstructures of Ag(30)Al(70) and Ag(40)Al(60) showed thinner and coarser ligament structures, respectively.