Browsing by Author "Bringa, Eduardo M."

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    Annealing twins in nanocrystalline fcc metals: A molecular dynamics simulation
    Farkas, Diana; Bringa, Eduardo M.; Caro, Alfredo (American Physical Society, 2007-05-23)
    We report fully three-dimensional atomistic molecular dynamics studies of grain growth kinetics in nanocrystalline Cu of 5 nm average grain size. We observe the formation of annealing twins as part of the grain growth process. The grain size and energy evolution was monitored as a function of time for various temperatures, yielding an activation energy for the process. The atomistic mechanism of annealing twin formation from the moving boundaries is described.
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    Sputtering from a porous material by penetrating ions
    Rodriguez-Nieva, J. F.; Bringa, Eduardo M.; Cassidy, T. A.; Johnson, R. E.; Caro, Alfredo; Fama, M.; Loeffler, M. J.; Baragiola, R. A.; Farkas, Diana (IOP Publishing Ltd., 2011-12-01)
    Porous materials are ubiquitous in the universe and weathering of porous surfaces plays an important role in the evolution of planetary and interstellar materials. Sputtering of porous solids in particular can influence atmosphere formation, surface reflectivity, and the production of the ambient gas around materials in space. Several previous studies and models have shown a large reduction in the sputtering of a porous solid compared to the sputtering of the non-porous solid. Using molecular dynamics simulations we study the sputtering of a nanoporous solid with 55% of the solid density. We calculate the electronic sputtering induced by a fast, penetrating ion, using a thermal spike representation of the deposited energy. We find that sputtering for this porous solid is, surprisingly, the same as that for a full-density solid, even though the sticking coefficient is high.