title: Diffusion on demand to control precipitation aging: application to Al-Mg-Si alloys.
abstract: We demonstrate experimentally that a part-per-million addition of Sn solutes in Al-Mg-Si alloys can inhibit natural aging and enhance artificial aging. The mechanism controlling the aging is argued to be vacancy diffusion, with solutes trapping vacancies at low temperature and releasing them at elevated temperature, which is supported by a thermodynamic model and first-principles computations of Sn-vacancy binding. This "diffusion on demand" solves the long-standing problem of detrimental natural aging in Al-Mg-Si alloys, which is of great scientific and industrial importance. Moreover, the mechanism of controlled buffering and release of excess vacancies is generally applicable to modulate diffusion in other metallic systems.
authors.affiliation: Laboratory of Metal Physics and Technology, Department of Materials, ETH Zurich, 8093 Zurich, Switzerland and Institute of Nonferrous Metallurgy, Montanuniversitaet Leoben, 8700 Leoben, Austria.
authors.forename: S
authors.initials: S
authors.lastname: Pogatscher
authors.affiliation: Institute of Nonferrous Metallurgy, Montanuniversitaet Leoben, 8700 Leoben, Austria.
authors.forename: H
authors.initials: H
authors.lastname: Antrekowitsch
authors.affiliation: Institute of Nonferrous Metallurgy, Montanuniversitaet Leoben, 8700 Leoben, Austria.
authors.forename: M
authors.initials: M
authors.lastname: Werinos
authors.affiliation: Laboratory of Metal Physics and Technology, Department of Materials, ETH Zurich, 8093 Zurich, Switzerland.
authors.forename: F
authors.initials: F
authors.lastname: Moszner
authors.affiliation: Scientific Center for Optical and Electron Microscopy ScopeM, ETH Zurich, 8093 Zurich, Switzerland.
authors.forename: S S A
authors.initials: SS
authors.lastname: Gerstl
authors.affiliation: Institute of Mechanical Engineering, EPFL, 1015 Lausanne, Switzerland.
authors.forename: M F
authors.initials: MF
authors.lastname: Francis
authors.affiliation: Institute of Mechanical Engineering, EPFL, 1015 Lausanne, Switzerland.
authors.forename: W A
authors.initials: WA
authors.lastname: Curtin
authors.affiliation: Laboratory of Metal Physics and Technology, Department of Materials, ETH Zurich, 8093 Zurich, Switzerland.
authors.forename: J F
authors.initials: JF
authors.lastname: Löffler
authors.affiliation: Laboratory of Metal Physics and Technology, Department of Materials, ETH Zurich, 8093 Zurich, Switzerland.
authors.forename: P J
authors.initials: PJ
authors.lastname: Uggowitzer