An atom-probe tomographic study of freckle formation in a nickel-based superalloy

Y. Amouyal, D. N. Seidman*

*Corresponding author for this work

Research output: Contribution to journalArticle

28 Scopus citations

Abstract

Freckles are misoriented defects formed during the solidification of single-crystal (SC) nickel-based superalloys, which are used for turbine blades in jet engines and power generators. Freckles can cause degradation in a turbine blade's mechanical properties at high temperatures, and their elimination is of prime technological importance. Employing atom-probe tomography (APT), analytical transmission electron microscopy and dual-beam focused ion-beam microscopy, the chemical compositions of dendritic cores and inter-dendritic regions for both the freckles and the base material in a multicomponent Ni-based alloy are analyzed. The densities of four liquid-compounds with the same compositions measured using APT are calculated, and it is demonstrated that the inter-dendritic liquids have considerably smaller densities than liquids with compositions the same as the dendritic cores. The latter serves as a quantitative measure for the likelihood of freckle formation.

Original languageEnglish (US)
Pages (from-to)6729-6742
Number of pages14
JournalActa Materialia
Volume59
Issue number17
DOIs
StatePublished - Oct 1 2011

Keywords

  • Atom-probe tomography
  • Directional solidification
  • Freckles
  • Nickel-based superalloys

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • Polymers and Plastics
  • Metals and Alloys

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