Creep properties and precipitate evolution in Al-Li alloys microalloyed with Sc and Yb

Matthew E. Krug, David N. Seidman, David C. Dunand*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

45 Scopus citations


A dilute Al-Sc alloy (Al-0.12 Sc, at.%, Al-Sc), its counterpart with a Li addition (Al-2.9 Li-0.11 Sc, at.%, Al-Li-Sc), as well as a quaternary alloy (Al-5.53 Li-0.048 Sc-0.009 Yb, at.%, Al-Li-Sc-Yb) were isothermally aged at 325°C, and in some cases isochronally aged to 450°C. As the α'-Al3(Li,Sc) and Al3(Li,Sc,Yb) precipitates, with L12 structure, coarsen in the two Li-containing alloys, their Li and Yb concentrations decrease and their Sc concentration increases. A significant interfacial excess of Li also segregates at the α-Al matrix/α'-Al3Sc(Li,Sc,Yb) precipitate interface: 5.99±0.05atomsnm-2 in Al-Li-Sc and 13.2±0.4atomsnm-2 in Al-Li-Sc-Yb after aging isochronally to 450°C. During compression creep at 300°C, the aged alloys exhibit threshold stresses between 8 and 22MPa. A recent threshold stress model based on elastic interactions between dislocations and precipitates predicts correctly that Li additions in the Al-Li-Sc alloy reduce the threshold stress, while Yb in the Al-Li-Sc-Yb alloy increases it. The model is also in agreement with the threshold stresses of all Al-Sc-X alloys published to date.

Original languageEnglish (US)
Pages (from-to)300-311
Number of pages12
JournalMaterials Science & Engineering A: Structural Materials: Properties, Microstructure and Processing
StatePublished - Jul 30 2012


  • Atom probe tomography
  • Lattice parameter mismatch
  • Mechanical properties (high-temperature deformation)
  • Rare-earth
  • Threshold stress

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering


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