Abstract
The physical and chemical properties shown by nanoporous metals, related to their unique structure, make them very promising for application in several fields. Recently, vapor-phase dealloying has been reported as a method for the preparation of several non-noble nanoporous metals, alternatively to dealloying in aqueous solutions. Using this approach, we have successfully fabricated nanoporous Al starting from an Al20Zn80 nanocomposite obtained by ball milling. The nanocomposite was annealed at 550 °C under high-vacuum conditions, and the difference in the vapor pressures allowed the selective removal of Zn by vapor-phase dealloying. The morphology of the resulting nanoporous material was analyzed by Scanning Electron Microscopy showing pores from few to thousands of nm; moreover, the nanoporous 3D structure was observed through Serial Block Face-Scanning Electron Microscopy. A specific surface area as high as 73 m2 g−1 was estimated by N2 physisorption measurements. In addition, a fractal model able to well reproduce the morphology of nanoporous Al was built. This model has been used for predicting mechanical properties which are in good agreement with experimental data obtained by nanoindentation.
Highlights
Porous materials can be defined as materials in which a fraction of the solid is replaced by pores [1]
We address the production of NP aluminum by vapor-phase dealloying (VPD) by treating an
From Serial Block Face-Scanning Electron Microscopy (SBF-SEM) analysis and by using image analysis (IA) techniques, it has been possible to estimate an additional porosity of 10% related to pores larger than 300 nm, which cannot be estimated by N2 physisorption measurements
Summary
Porous materials can be defined as materials in which a fraction of the solid is replaced by pores [1]. Its bicontinuous nanoporous structure confers to NP Au better mechanical properties than corresponding bulk metals; its high costs hinder the use of this material for structural applications In this regard, the ability to fabricate other metals in NP form is crucial in order to facilitate their access to commercial applications, such as structural ones. Relevant applications of fractal modeling show its reliability to reproduce structure features of several materials, and to predict their behavior under different conditions [25,26,27] In this case, it has been possible to calculate the specific surface (by simple geometrical measurements) and Young’s modulus (by resolving series and parallel springs’ patterns after model conversion), which have been successfully compared with experimental measurements
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