Precipitation evolution in Al-Zr and Al-Zr-Ti alloys during aging at 450-600 °C

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

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

174 Scopus citations

Abstract

The transformation of Al3Zr (L12) and Al3(Zr1-xTix) (L12) precipitates to their respective equilibrium D023 structures is investigated in conventionally solidified Al-0.1Zr and Al-0.1Zr-0.1Ti (at.%) alloys aged isothermally at 500 °C or aged isochronally in the range 300-600 °C. Titanium additions delay neither coarsening of the metastable L12 precipitates nor their transformation to the D023 structure. Both alloys overage at the same rate at or above 500 °C, during which spheroidal L12 precipitates transform to disk-shaped D023 precipitates at ca. 200 nm in diameter and 50 nm in thickness, exhibiting a cube-on-cube orientation relationship with the α-Al matrix. The transformation occurs heterogeneously on dislocations because of a large lattice parameter mismatch of the D023 phase with α-Al. The transformation is very sluggish and even at 575 °C coherent L12 precipitates can remain untransformed. Mechanisms of microstructural coarsening and strengthening are discussed with respect to the micrometer-scale dendritic distribution of precipitates.

Original languageEnglish (US)
Pages (from-to)1182-1195
Number of pages14
JournalActa Materialia
Volume56
Issue number6
DOIs
StatePublished - Apr 2008

Keywords

  • Aluminum alloys
  • Coarsening
  • Precipitation strengthening
  • Titanium
  • Zirconium

ASJC Scopus subject areas

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

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