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 degrees C, to form L1(2)-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 similar to 1-10. First-principles calculations demonstrate that the formation energies of substitutional W atoms in the L1(2) lattices are high and positive (0.66 - 1.73 eV.atom(-1)), consistent with the small W solubilities measured experimentally in these nanoprecipitates. (C) 2019 Elsevier B.V. All rights reserved.