Microstructural stability of an Ni-Mo based Hastelloy after 10 MeV electron irradiation at high temperature

Nelia Wanderka*, Dieter Isheim, Alexander Bakai, Christian Abromeit, David N Seidman

*Corresponding author for this work

Research output: Contribution to journalArticle

1 Scopus citations

Abstract

The microstructural changes of a Hastelloy alloy under 10 MeV electron irradiation at 650 °C for 700 h to a total fluence of 2 × 10 -3 dpa (displacements per atom) were investigated by transmission electron microscopy and by 3- dimensional atom-probe tomography utilizing a local-electrode atom-probe tomograph. Transmission electron microscopy analysis before irradiation reveals two types of precipitates: (i) spheroidal with a mean diameter of 22 nm; and (ii) ones with an irregular morphology of a few nm in diameter. The spheroidal precipitates (i) are coherent with the fcc matrix and their number density is ̃3 ×1021 m-3. Electron diffraction patterns from these precipitates exhibit superlattice reflections corresponding to the L12 ordered structure. The chemical composition as measured by atomprobe tomography, is about 75 at.% Ni with additions of Al, Ti and Mo. The other type of precipitate (ii) is mainly enriched in Ni and Mo and its number density is ca. 3.6 · 1022 m-3. The diffuse diffraction intensity maxima arising from these precipitates are observed at <11/20>fcc, which are attributed to compositional short-range order. After electron irradiation, the Ni -Al-rich precipitates (i) exhibiting L12 superlattice reflections have disappeared completely, while the diffuse intensity maxima from the Ni -Mo rich clusters (ii) are still visible. The results are discussed with respect to the influence of the electron irradiation on the morphology and structural changes of the ordered precipitates.

Original languageEnglish (US)
Pages (from-to)631-636
Number of pages6
JournalInternational Journal of Materials Research
Volume101
Issue number5
DOIs
StatePublished - May 28 2010

Keywords

  • APT
  • Electron irradiation
  • Hastelloy alloy
  • Microstructure
  • TEM

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Physical and Theoretical Chemistry
  • Metals and Alloys
  • Materials Chemistry

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