Strain development in nanoporous metallic foils formed by dealloying

Nanoporous Au foils were formed by dealloying a Ag-Au alloy in concentrated HNO3. The resultant foils, which have a spongelike morphology with interconnecting ligaments, were studied using synchrotron-based diffraction. A three-dimensional visualization of the nanostructure is generated from small angle experiments and the lattice parameter is derived from diffraction. The data show the development of two interspersed nanoscale strained regions within the material: one in significant tension and one in compression. We interpret this by considering regions of high positive and negative curvatures in the material; this curvature decreases with increasing pore size resulting in a relaxation in lattice strain. (C) 2008 American Institute of Physics.