SEDL / STP / STP1447-EB / STP11251S

Bubble Microstructures in Helium Injected Palladium Foils

Gelles, DS
Staff Engineer, Richland, WA

Causey, RA
Staff, Sandia National Laboratories, Livermore, CA

Hertz, K
Staff, Sandia National Laboratories, Livermore, CA

Cowgill, DF
Staff, Sandia National Laboratories, Livermore, CA

Schäublin, R
Staff, EPFL-CRPP Fusion Technology,

Pages: 10    Published: Jan 2004

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Abstract

Microstructural characterization of helium bubble distributions is provided for a series of palladium foils that were injected with ³He under varying conditions of dose, temperature and starting foil condition. Specimens were prepared in cross section and bubble layers ∼500 nm thick are found starting ∼300 nm from foil surfaces. Bubble densities and sizes were found to vary with foil microstructure and injection conditions, with larger bubbles formed on microstructural features such as sub-grain boundaries and nearer the surface. Most surprisingly, bubble sizes are found to be as small as 1 to 2 nm in diameter. Specimen preparation details and imaging issues for very small bubbles are discussed.