<Abstrate>

A study of the isothermal evolution of a nanoporous gold (npg) microstructure

after dealloying has been performed. In order to adequately characterize its complex

three-dimensional bicontinuous ligament-ring structure, an analysis of the scaled

principle curvatures κ₁ and κ₂ based on representative volumes of meshed 3D

reconstructions was applied. Five npg samples, as obtained from an electrolytical

dealloying process, with different mean ligament diameters ranging from ca. 25

 nm (as-dealloyed) to ca. 420 nm (from annealing at 300° C) were analyzed.

The results indicate that ligament surface flattening effects lead to small but distinct

morphological changes during the investigated early and mid-stages of coarsening,

visible in the scaled κ₁- and κ₂- marginal distributions. Thus, strictly speaking,

self-similar evolution of npg cannot be confirmed, but dependent on the specific

application, the evolution might be seen as “sufficiently” self-similar. Moreover,

it is shown that the inverse mean principle curvatures from the marginal

distributions can be used to identify the mean sizes of the two salient structural

features, namely the ligaments and the rings. Both inverse mean principle curvatures

scale linearly with the mean ligament diameter. Thus, for the material used in this

study, one parameter is sufficient to characterize its microstructure. Finally, it is shown

that rings resembling the ones from the real samples can be generated computationally

by applying modified torus parameterizations. Surprisingly, a calculation of the

curvature distribution of only one ”average” ring is sufficient to approximate the

scaled kappa distributions accumulated from the ring distributions of the real samples.
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