Fabrication of a bimodal micro/nanoporous metal by the Gasar and dealloying processes

Abstract

A combination of the Gasar and dealloying processes for fabricating a bimodal micro/nanoporous metal was proposed. Lotus-type, porous Cu–34.6wt% Mn alloy was prepared by metal–gas eutectic unidirectional solidification, i.e., the Gasar process. This Gasar Cu–Mn alloy was then subjected to dealloying treatment, and nanoporous Cu was prepared at various current levels and durations. Two different dealloyed porous structures, namely haystack and sponge-like form, were obtained at low (≤100mA) and high (≥1A) current levels, respectively. The distinct morphology can be attributed to the changes in the reaction rate and surface diffusion coefficient (DS). Thus dealloying current determines the pore morphology.