Effects of a tungsten addition on the morphological evolution, spatial correlations and temporal evolution of a model Ni-Al-Cr superalloy

Chantal K. Sudbrack, Tiffany D. Ziebell, Ronald D. Noebe, David N. Seidman*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

77 Scopus citations

Abstract

The effect of adding 2 at.% W to a model Ni-Al-Cr superalloy on the morphological evolution, spatial correlations and temporal evolution of γ′(L12)-precipitates at 1073 K is studied with scanning electron microscopy and atomic force microscopy. Adding W yields a larger microhardness, earlier onset of spheroidal-to-cuboidal precipitate morphological transition, larger volume fraction (from ∼20% to 30%), reduction in coarsening kinetics by one-third and a larger number density (Nv) of smaller mean radii (〈R〉) precipitates. The kinetics of 〈R〉 and interfacial area per unit volume obey t1/3 and t-1/3 relationships, respectively, which is consistent with coarsening driven by interfacial energy reduction. The Nv power-law dependencies deviate, however, from model predictions, indicating that a stationary state is not achieved. Quantitative analyses with precipitate size distributions, pair correlation functions and edge-to-edge interprecipitate distance distributions give insight into two-dimensional microstructural evolution, including the elastically driven transition from a uniform γ′-distribution to one-dimensional 〈0 0 1〉-strings to eventually clustered packs of γ′-precipitates in the less densely packed Ni-Al-Cr alloy.

Original languageEnglish (US)
Pages (from-to)448-463
Number of pages16
JournalActa Materialia
Volume56
Issue number3
DOIs
StatePublished - Feb 2008

Keywords

  • Coarsening
  • Nanostructure
  • Nickel alloys
  • Precipitation
  • Tungsten

ASJC Scopus subject areas

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

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