Ambient- and high-temperature mechanical properties of isochronally aged Al-0.06Sc, Al-0.06Zr and Al-0.06Sc-0.06Zr (at.%) alloys

Keith E. Knipling, David N Seidman, David C Dunand

Research output: Contribution to journalArticle

161 Scopus citations

Abstract

Ambient- and high-temperature precipitation strengthening are investigated in Al-0.06Sc, Al-0.06Zr and Al-0.06Sc-0.06Zr (at.%) alloys. Following solidification, Sc is concentrated at the dendrite peripheries while Zr is segregated at the dendrite cores. During isochronal aging, precipitation of Al3Sc (L12) commences between 250 and 300 °C for Al-0.06Sc, and reaches a 429 MPa peak microhardness at 325 °C. For Al-0.06Zr, precipitation of Al3Zr (L12) first occurs between 400 and 425 °C and reaches a 295 MPa peak microhardness at 475 °C. A pronounced synergistic effect is observed when both Sc and Zr are present. Above 325 °C, Zr additions provide a secondary strength increase that is attributed to precipitation of Zr-enriched outer shells onto the Al 3Sc precipitates, leading to a peak microhardness of 618 MPa at 400 °C for Al-0.06Sc-0.06Zr. Upon compressive creep deformation at 300-400 °C, Al-0.06Sc-0.06Zr exhibits threshold stresses of 7-12 MPa; these values may be further improved by optimal heat-treatments.

Original languageEnglish (US)
Pages (from-to)943-954
Number of pages12
JournalActa Materialia
Volume59
Issue number3
DOIs
StatePublished - Feb 1 2011

Keywords

  • Aluminum alloys
  • Isochronal heat-treatments
  • 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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