Precipitation evolution in Al-0.1Sc, Al-0.1Zr and Al-0.1Sc-0.1Zr (at.%) alloys during isochronal aging

Keith E. Knipling, Richard A. Karnesky, Constance P. Lee, David C. Dunand, David N. Seidman

Research output: Contribution to journalArticlepeer-review

399 Scopus citations


Precipitation strengthening is investigated in binary Al-0.1Sc, Al-0.1Zr and ternary Al-0.1Sc-0.1Zr (at.%) alloys aged isochronally between 200 and 600 °C. Precipitation of Al3Sc (L12) commences between 200 and 250 °C in Al-0.1Sc, reaching a 670 MPa peak microhardness at 325 °C. For Al-0.1Zr, precipitation of Al3Zr (L12) initiates between 350 and 375 °C, resulting in a 420 MPa peak microhardness at 425-450 °C. A pronounced synergistic effect is observed when both Sc and Zr are present. Above 325 °C, Zr additions provide a secondary strength increase from the precipitation of Zr-enriched outer shells onto the Al 3Sc precipitates, leading to a peak microhardness of 780 MPa at 400 °C for Al-0.1Sc-0.1Zr. Compositions, radii, volume fractions and number densities of the Al3(Sc1-xZrx) precipitates are measured directly using atom-probe tomography. This information is used to quantify the observed strengthening increments, attributed to dislocation shearing of the Al3(Sc1-xZrx) precipitates.

Original languageEnglish (US)
Pages (from-to)5184-5195
Number of pages12
JournalActa Materialia
Issue number15
StatePublished - Sep 2010


  • Aluminum alloys
  • Atom-probe tomography
  • Precipitation
  • Scandium
  • Zirconium

ASJC Scopus subject areas

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


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