Composition evolution of nanoscale Al3Sc precipitates in an Al-Mg-Sc alloy: Experiments and computations

Emmanuelle A. Marquis, David N. Seidman*, Mark Asta, Christopher Woodward

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

91 Scopus citations


Controlling the distribution of chemical constituents within complex, structurally heterogeneous systems represents one of the fundamental challenges of alloy design. We demonstrate how the combination of recent developments in sophisticated experimental high resolution characterization techniques and ab initio theoretical methods provide the basis for a detailed level of understanding of the microscopic factors governing compositional distributions in metallic alloys. In a study of the partitioning of Mg in two-phase ternary Al-Sc-Mg alloys by atom-probe tomography, we identify a large Mg concentration enhancement at the coherent α-Al/Al3Sc heterophase interface with a relative Gibbsian interfacial excess of Mg with respect to Al and Sc, ΓMgrel, equal to 1.9 ± 0.5 atom nm-2. The corresponding calculated value of ΓMgrel is ∼1.2 atom nm-2. Theoretical ab initio investigations establish an equilibrium driving force for Mg interfacial segregation that is primarily chemical in nature and reflects the strength of the Mg-Sc interactions in an Al-rich alloy.

Original languageEnglish (US)
Pages (from-to)119-130
Number of pages12
JournalActa Materialia
Issue number1
StatePublished - Jan 2006


  • Ab initio calculations
  • AlSc precipitates
  • Atom-probe tomography
  • Coherent heterophase interface
  • Mg segregation

ASJC Scopus subject areas

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


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