Microstructural evolution and creep properties of precipitation- strengthened Al-0.06Sc-0.02Gd and Al-0.06Sc-0.02Yb (at.%) alloys

Marsha E. Van Dalen, David C. Dunand, David N. Seidman

Research output: Contribution to journalArticle

41 Scopus citations

Abstract

The aging behavior at 300 °C of Al-0.06Sc-0.02Gd and Al-0.06Sc-0.02Yb (at.%) alloys is studied by local-electrode atom-probe tomography, transmission electron microscopy and microhardness measurements. The ternary alloys exhibit high number densities of coherent L12 precipitates ( Nv≅1022m-3) at aging times up to 1536 h (64 days). In the Al-0.06Sc-0.02Gd alloy, the Al3(Sc 1-xGdx) precipitates are always Sc-rich, displaying a small Gd concentration (x < 0.12) in the precipitates. In the Al-0.06Sc-0.02Yb alloy, the precipitates are initially Yb-rich, Al 3(Yb1-xScx), with Sc diffusing subsequently to the precipitates, resulting in a core/shell structure and an overall Sc-rich composition, Al3(Sc1-xYb x). Gd and Yb, like other lanthanides but unlike the transition metals Zr and Ti, do not retard the coarsening kinetics compared with binary Al-Sc alloys. Additionally, the creep resistance of these alloys is greater than that of Al-Sc alloys. The coarsening kinetics and creep properties of Al-0.06Sc-0.02Gd and Al-0.06Sc-0.02Yb alloys are compared with other Al-Sc-based alloys and with coarsening models for ternary alloys.

Original languageEnglish (US)
Pages (from-to)5224-5237
Number of pages14
JournalActa Materialia
Volume59
Issue number13
DOIs
StatePublished - Aug 1 2011

Keywords

  • Aluminum alloys
  • Coarsening
  • Creep
  • Nucleation
  • Precipitation

ASJC Scopus subject areas

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

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