Characterization and Yield behavior of UFG, Nano-Twinned Copper

Andrea M. Hodge Materials ScientistNanoscale Synthesis and Characterization
LaboratoryLawrence Livermore National Laboratory Livermore, CA Yield point drops are a classic non-uniform plastic deformation process in solids. As stated by Johnston and Gilman in their classic work on single crystal Lithium Fluoride, the yield point drop phenomena in crystalline solids is clearly dependant on the availability of necessary mobile dislocations to support the plastic deformation process. In this talk, the presence of a yield point will be related to materials with nanocrystalline, ultrafine-grained (UFG) and evenly distributed nanoscale features (i.e. twins). Specifically, tensile tests performed on high purity (99.999%) copper foils (170 m thick), processed by magnetron sputtered multilayer technology, demonstrate reproducible observations of yield points. These type of materials present very low initial dislocation densities, a columnar grain structure (~ 0.55 m width), and uniformly distributed and spaced (? 45 to 50 nm) growth twins with an orientation parallel to the plane of deposition.

Location: Seaver Science Library, Room 150

Audiences: Everyone Is Invited

Contact: April Mundy