Materials Science Research Lecture
Abstract: Nanoporous metals have a broad range of applications such as catalyst supports, artificial muscles, and battery electrodes. The size-scale of these bicontinuous mixtures of metal and void can be controlled by isothermal coarsening. However, the effects of coarsening on the morphology and topology (connectivity) of the metal-vapor interfaces are poorly understood, and thus it is difficult to link the processing of nanoporous metals to their properties. In an effort to understand the factors setting the morphology of the interfaces nanoporous metals, we employ experimental measurements of the three-dimensional morphology of nanoporous gold. These results are then compared with large-scale phase field simulations of the coarsening of bicontinuous two-phase mixtures. The simulations show that during coarsening bicontinuous two-phase mixtures attain a universal self-similar morphology and topology that can thus can be compared directly to nanoporous gold. We find dramatic changes in the morphology and topology of bicontinuous structures for volume fractions of solid just above the critical value at which bicontinuity is lost. A comparison between the simulations and experiments shows the critical role of the volume fraction of metal in setting the morphology and topology of the nanoporous metals.
More about the speaker: Peter Voorhees is the Frank C. Engelhart Professor of Materials Science and Engineering at Northwestern University, and Professor of Engineering Sciences and Applied Mathematics. He is co-director of the Northwestern-Argonne Institute of Science and Engineering and is a Director of the Center for Hierarchical Materials Design. He received his Ph.D. in Materials Engineering from Rensselaer Polytechnic Institute and was a member of the Metallurgy Division at the National Institute for Standards and Technology until joining the Department of Materials Science and Engineering at Northwestern University. He has received numerous awards including the National Science Foundation Presidential Young Investigator Award, ASM International Materials Science Division Research Award (Silver Medal), the TMS Bruce Chalmers Award, the ASM J. Willard Gibbs Phase Equilibria Award, and the McCormick School of Engineering and Applied Science Award for Teaching Excellence. Professor Voorhees is a fellow of ASM International, the Minerals, Metals and Materials Society, and the American Physical Society. He is a member of the American Academy of Arts and Sciences. He has published over 250 papers in the area of the thermodynamics and kinetics of phase transformations.