Roles of impurities on precipitation kinetics of dilute Al-Sc alloys

Ofer Beeri*, David C Dunand, David N Seidman

*Corresponding author for this work

Research output: Contribution to journalArticle

32 Scopus citations

Abstract

High-purity (HP) aluminum and commercial purity (CP) aluminum (major impurities: ∼250at.ppm Si and ∼130at.ppm Fe) are alloyed with ∼250 to ∼1100at.ppm Sc and ∼50at.ppm RE (RE=La, Ce, Pr, or Nd). The alloys are homogenized at 640°C and aged at 300°C. The precipitation kinetics, basic mechanical properties, and microstructure are studied using AC electrical conductivity, microhardness measurements, scanning electron microscopy in conjunction with energy dispersive X-ray spectroscopy, and atom-probe tomography, respectively. The Fe and RE elements form micrometer-scale diameter Al∼3(Fe,RE) primary precipitates, which have no effect on the mechanical properties. Silicon accelerates the precipitation kinetics of nanometer-scale diameter Al3Sc precipitates, increasing their number density, thereby resulting in higher microhardness values for CP aluminum than the HP aluminum having the same Sc concentration. Additionally, the Sc equilibrium solubility in the α-Al matrix is estimated and Orowan's strengthening mechanism is confirmed for the Al3Sc precipitates.

Original languageEnglish (US)
Pages (from-to)3501-3509
Number of pages9
JournalMaterials Science and Engineering A
Volume527
Issue number15
DOIs
StatePublished - Jun 1 2010

Keywords

  • Atom probe
  • Dilute aluminum alloys
  • Impurities
  • Precipitation
  • Scandium

ASJC Scopus subject areas

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

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