Edge energies and shapes of nanoprecipitates.

Hamilton, John C.

Sandia National Laboratories

关键词: Aluminium;    Inclusions Nanoparticles.;    Nanostructures;    Lead;    36 Materials Science;   

DOI  :  10.2172/902203
RP-ID  :  SAND2007-0238
RP-ID  :  AC04-94AL85000
RP-ID  :  902203

美国|英语

来源: UNT Digital Library

【 摘 要 】

In this report we present a model to explain the size-dependent shapes of lead nano-precipitates in aluminum. Size-dependent shape transitions, frequently observed at nanolength scales, are commonly attributed to edge energy effects. This report resolves an ambiguity in the definition and calculation of edge energies and presents an atomistic calculation of edge energies for free clusters. We also present a theory for size-dependent shapes of Pb nanoprecipitates in Al, introducing the concept of ''magic-shapes'' defined as precipitate shapes having near zero elastic strains when inserted into similarly shaped voids in the Al matrix. An algorithm for constructing a complete set of magic-shapes is presented. The experimental observations are explained by elastic strain energies and interfacial energies; edge energies play a negligible role. We replicate the experimental observations by selecting precipitates having magic-shapes and interfacial energies less than a cutoff value.