Precipitation strengthening at ambient and elevated temperatures of heat-treatable Al(Sc) alloys

David N. Seidman*, Emmanuelle A. Marquis, David C. Dunand

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

439 Scopus citations

Abstract

Yield strength at ambient temperature and creep resistance between 225 and 300°C were investigated in dilute Al(Sc) alloys containing coherent Al3Sc precipitates, which were grown by heat-treatments to radii in the range 1.4-9.6 nm. The dependence of the ambient-temperature yield stress on precipitate size is explained using classical precipitation strengthening theory, which predicts a transition from precipitate shearing to Orowan dislocation looping mechanisms at a precipitate radius of 2.1 nm, in good agreement with experimental data. At 300°C creep threshold stresses are observed and found to be much lower than the yield stresses, indicative of a climb-controlled bypass mechanism. The threshold stress increases with increasing precipitate radius, in qualitative agreement with a climb model taking into account stiffness and lattice mismatches between matrix and precipitates.

Original languageEnglish (US)
Pages (from-to)4021-4035
Number of pages15
JournalActa Materialia
Volume50
Issue number16
DOIs
StatePublished - Sep 20 2002

Keywords

  • Aluminum alloys
  • Creep
  • Mechanical properties
  • Precipitation strengthening
  • Scandium
  • Threshold stress

ASJC Scopus subject areas

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

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