Mechanical Behaviour of Nanoporous Gold: Influence of Morphology
Final Report Abstract
This study successfully captures the structure-property relations in nanoporous gold (np-Au) by incorporating quantitative architectural information into the foam scaling laws. By quantifying the three-dimensional structure obtained from focused ion beam nanotomography, we have shown that application of potential during dealloying of the precursor alloy, or thermal coarsening of dealloyed structures, has no significant influence on the morphology and topology of np-Au. Some variations in the topology are present among structures which are random variations and we show that these can be directly correlated with variations in their mechanical properties. The elastic modulus from the finite element simulations on the tomographic reconstructions is in excellent agreement with the nanoindentation experiments, thus validating the modelling procedure. One of the important findings of this study is that the elastic modulus and strength of np-Au are linearly dependent on the experimentally quantifiable-structural topology characterized in terms of scaled genus density. Modified scaling relations for the modulus and strength are thus obtained. We present a direct study of the multiaxial response of np-Au for the first time. Multiaxial loading simulations on tomographic structures revealed that the elastic response is isotropic. These simulations also reveal that the initial yield response of np-Au is similar to the conventional engineering foams for mean stressdominated loadings, while differs if the loading is shear-dominated. Comparison of the multiaxial yield data with literature foam yield criterion has led to a very useful result: the hardness from nanoindentation is roughly 2.7 times the uniaxial yield or flow stress of np-Au, in contrast to the generally assumed nearequality of the two quantities.
Publications
- “Multiscale modeling of charge-induced deformation of nanoporous gold structures”, J. Mech. Phys, Solids, 66, p1-16, 2014
S.S.R. Saane, K.R. Mangipudi, K.U. Loos, J.Th.M. De Hosson, P.R. Onck
(See online at https://doi.org/10.1016/j.jmps.2014.01.007) - “A FIB-nanotomography method for accurate 3D reconstruction of open nanoporous structures”, Ultramicroscopy, 163, p38-47, 2016
K.R. Mangipudi, V. Radisch, L. Holzer, C.A. Volkert
(See online at https://doi.org/10.1016/j.ultramic.2016.01.004) - “Crystal plasticity study of monocrystalline stochastic honeycombs under in-plane compression”, Acta Mater., 103, pp796-808, 2016
D. Ma, P. Eisenlohr, E. Epler, C.A. Volkert, P. Shanthraj, M. Diehl, F. Roters, D. Raabe
(See online at https://doi.org/10.1016/j.actamat.2015.11.016) - “Topology-dependent scaling laws for the stiffness and strength of nanoporous gold”, Acta Mater., 119, p115-122, 2016
K.R. Mangipudi, E. Epler, C.A. Volkert
(See online at https://doi.org/10.1016/j.actamat.2016.08.012)
