title: Mapping the evolution of hierarchical microstructures in a Ni-based superalloy.
abstract: Phase separation of γ' precipitates determines the microstructure and mechanical properties of nickel-based superalloys. In the course of ageing, disordered γ spheres form inside ordered (L12) γ' precipitates, undergo a morphological change to plates and finally split the γ' precipitates. The presence of γ particles inside γ' affects coarsening kinetics and increases alloy hardness. Here we use atom probe tomography to visualize phase separation in a Ni86.1Al8.5Ti5.4 alloy in three dimensions and to quantify the composition of all the phases with near-atomic resolution. We find that γ' precipitates are supersaturated in nickel, thereby driving the formation of γ particles and observe a compositional evolution of the γ particles, which accompanies their morphological change. Our results suggest that by controlling nickel supersaturation we can tailor the phase separation and thereby the properties of nickel-based superalloys.
authors.affiliation: Institute of Applied Materials, Helmholtz-Zentrum Berlin, Hahn-Meitner-Platz 1, 14109 Berlin, Germany.
authors.forename: Florian
authors.initials: F
authors.lastname: Vogel
authors.affiliation: Institute of Applied Materials, Helmholtz-Zentrum Berlin, Hahn-Meitner-Platz 1, 14109 Berlin, Germany.
authors.forename: Nelia
authors.initials: N
authors.lastname: Wanderka
authors.affiliation: Institute of Materials Physics, University of Münster, Wilhelm-Klemm-Str. 10, 48149 Münster, Germany.
authors.forename: Zoltan
authors.initials: Z
authors.lastname: Balogh
authors.affiliation: Institute of Materials Physics, University of Münster, Wilhelm-Klemm-Str. 10, 48149 Münster, Germany.
authors.forename: Mohammed
authors.initials: M
authors.lastname: Ibrahim
authors.affiliation: Institute of Materials Physics, University of Münster, Wilhelm-Klemm-Str. 10, 48149 Münster, Germany.
authors.forename: Patrick
authors.initials: P
authors.lastname: Stender
authors.affiliation: Institute of Materials Physics, University of Münster, Wilhelm-Klemm-Str. 10, 48149 Münster, Germany.
authors.forename: Guido
authors.initials: G
authors.lastname: Schmitz
authors.affiliation: 1] Institute of Applied Materials, Helmholtz-Zentrum Berlin, Hahn-Meitner-Platz 1, 14109 Berlin, Germany [2] Department of Materials Science and Technology, Technische Universität Berlin, Hardenberg-Str. 36, 10623 Berlin, Germany.
authors.forename: John
authors.initials: J
authors.lastname: Banhart