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

A combination of the Gasar and dealloying processes for fabricating a bimodal micro/nanoporous metal was proposed. Lotus-type, porous Cu-34.6 wt% 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 (<= 100 mA) and high (>= 1 A) current levels, respectively. The distinct morphology can be attributed to the changes in the reaction rate and surface diffusion coefficient (D-S). Thus dealloying current determines the pore morphology. (C) 2012 Elsevier B.V. All rights reserved.