Atom probe tomographic studies of precipitation in Al-O. 1Zr-O. 1Ti (at.%) alloys

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

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

28 Scopus citations


Atom probe tomography was utilized to measure directly the chemical compositions of Al3(Zr1-xTix) precipitates with a metastable Ll2 structure formed in Al-0. 1Zr-0.1Ti (at.%) alloys upon aging at 375°C or 425°C. The alloys exhibit an inhomogeneous distribution of Al3(Zr1-xTix) precipitates, as a result of a nonuniform dendritic distribution of solute atoms after casting. At these aging temperatures, the Zr:Ti atomic ratio in the precipitates is about 10 and 5, respectively, indicating that Ti remains mainly in solid solution rather than partitioning to the Al3(Zr1-xTix) precipitates. This is interpreted as being due to the very small diffusivity of Ti in α-Al, consistent with prior studies on Al-Sc-Ti and Al-Sc-Zr alloys, where the slower diffusing Zr and Ti atoms make up a small fraction of the Al3(Sc1-x/Tix/Zrx) precipitates. Unlike those alloys, however, the present Al-Zr-Ti alloys exhibit no interfacial segregation of Ti at the matrix/precipitate heterophase interface, a result that may be affected by a significant disparity in the evaporation fields of the α-Al matrix and Al3(Zr1-xTix) precipitates and/or a lack of local thermodynamic equilibrium at the interface.

Original languageEnglish (US)
Pages (from-to)503-516
Number of pages14
JournalMicroscopy and Microanalysis
Issue number6
StatePublished - Dec 2007


  • Al-Zr-Ti
  • AlZr precipitates
  • Atom probe tomography
  • Local magnification

ASJC Scopus subject areas

  • Instrumentation


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