Tungsten solubility in L12-ordered Al3Er and Al3Zr nanoprecipitates formed by aging in an aluminum matrix

The partitioning behavior of tungsten is studied in two dilute Al-Er-W and Al-Zr-W alloys aged isochronally up to 400 and 475 °C, to form L12-structured Al3Er and Al3Zr nanoprecipitates. Atom-probe tomography reveals low W solubility in the Al3Er and Al3Zr nanoprecipitates (0.071 and 0.234 at.%, respectively) and very low W solubility in the Al matrix (0.057 and 0.023 at.%, respectively), corresponding to precipitate/matrix partitioning ratios of ∼1–10. First-principles calculations demonstrate that the formation energies of substitutional W atoms in the L12 lattices are high and positive (0.66–1.73 eV.atom−1), consistent with the small W solubilities measured experimentally in these nanoprecipitates. •L12-nanoprecipitates formed upon aging the dilute Al-Zr-W and Al-Er-W alloys.•A limited solubility of W in the L12-phase was observed experimentally.•W prefers strongly to occupy the Al sublattice sites of L12-Al3Zr.•W weakly prefers to substitute at the Er sublattice sites of L12-Al3Er.•These substitutions are associated with large and positive formation energies.