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Microstructural features in aged erbium tritide films

ASTM Special Technical Publication

Gelles, D.S.; Brewer, Luke N.; Kotula, Paul G.; Cowgill, D.F.; Busick, Carla C.; Snow, C.S.

Erbium is used as a storage medium for tritium. Microstructural study of helium bubble generation from tritium decay in erbium tritide can provide an unusual example of bubble development with negligible radiation damage. Aged erbium tritide film specimens were found to contain five distinctly different microstructural features. The general structure was of large columnar grains of ErT2. But on a fine scale, precipitates believed to be erbium oxy-tritides and helium bubbles could be identified. The precipitate size was in the range of ∼10 nm and the bubbles were of an unusual planar shape on {111} planes with an invariant thickness of ∼1 nm and a diameter on the order of 10 nm. Also, an outer layer containing no fine precipitate structure and only a few helium bubbles were present on the films. This layer is best described as a denuded zone which probably grew during aging in air. Finally, large embedded Er2O3 particles were found at low density and nonuniformly distributed, but sometimes extending through the thickness of the film. A failure mechanism allowing the helium to escape is suggested by observed cracking between bubbles closer to end of life. Copyright © 2007 by ASTM International.

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TYPE Conference YEAR 2008
ScopusOSTI

Helium release and microstructural changes in Er(D,T)2-x3Hex films)

Snow, Clark S.; Brewer, Luke N.; Rodriguez, Marko A.; Kotula, Paul G.; Banks, J.C.; Mangan, Michael M.

Er(D,T){sub 2-x} {sup 3}He{sub x}, erbium di-tritide, films of thicknesses 500 nm, 400 nm, 300 nm, 200 nm, and 100 nm were grown and analyzed by Transmission Electron Microscopy, X-Ray Diffraction, and Ion Beam Analysis to determine variations in film microstructure as a function of film thickness and age, due to the time-dependent build-up of {sup 3}He in the film from the radioactive decay of tritium. Several interesting features were observed: One, the amount of helium released as a function of film thickness is relatively constant. This suggests that the helium is being released only from the near surface region and that the helium is not diffusing to the surface from the bulk of the film. Two, lenticular helium bubbles are observed as a result of the radioactive decay of tritium into {sup 3}He. These bubbles grow along the [111] crystallographic direction. Three, a helium bubble free zone, or 'denuded zone' is observed near the surface. The size of this region is independent of film thickness. Four, an analysis of secondary diffraction spots in the Transmission Electron Microscopy study indicate that small erbium oxide precipitates, 5-10 nm in size, exist throughout the film. Further, all of the films had large erbium oxide inclusions, in many cases these inclusions span the depth of the film.

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TYPE SAND Report YEAR 2007
OSTIDOI

Structure and properties of Ni/Ti thin films used for brazing

Proceedings of the 3rd International Brazing and Soldering Conference

Adams, D.P.; Bai, M.M.; Rodriguez, Marko A.; Moore, J.J.; Brewer, Luke N.; Kelley, J.B.

The properties of energetic thin films considered for alternative braze[1] techniques are investigated. Vapor-deposited Ni/Ti multilayer foils having a net 1:1 stoichiometry exhibit self-propagating, high temperature combustion reactions. The rate of reaction depends on Ni/Ti multilayer design with steady-state propagation speeds of freestanding foils measured from 0.2 to 1.0m/s. Transmission electron microscopy and x-ray diffraction further show that NiTi films reacted in a self-propagating mode have a fine-grain, polycrystalline microstructure. All films are composed of cubic B2 and monoclinic B19' phases with some having NiTi2 or Ni3Ti precipitates. Copyright © 2006 ASM International®.

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TYPE Conference YEAR 2006
ScopusOSTI
Results 26–50 of 55
Results 26–50 of 55