title: Self-organized Sr leads to solid state twinning in nano-scaled eutectic Si phase.
abstract: A new mechanism for twin nucleation in the eutectic Al-Si alloy with trace Sr impurities is proposed. Observations made by sub-angstrom resolution scanning transmission electron microscopy and X-ray probing proved the presence of <110> Sr columns located preferentially at twin boundaries. Density functional theory simulations indicate that Sr atoms bind in the Si lattice only along the <110> direction, with preferential positions at first and second nearest neighbors for interstitial and substitutional Sr, respectively. Density functional theory total energy calculations confirm that twin nucleation at Sr columns is energetically favorable. Hence, twins may nucleate in Si precipitates after solidification, which provides a different perspective to the currently accepted mechanism which suggests twin formation during precipitate growth.
authors.affiliation: Graz Centre of Electron Microscopy, Steyrergasse 17/III, 8010 Graz, Austria.
authors.forename: M
authors.initials: M
authors.lastname: Albu
authors.affiliation: Department of Mechanical, Aerospace and Nuclear Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180, USA.
authors.forename: A
authors.initials: A
authors.lastname: Pal
authors.affiliation: Graz Centre of Electron Microscopy, Steyrergasse 17/III, 8010 Graz, Austria.
authors.forename: C
authors.initials: C
authors.lastname: Gspan
authors.affiliation: Department of Mechanical, Aerospace and Nuclear Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180, USA.
authors.forename: R C
authors.initials: RC
authors.lastname: Picu
authors.affiliation: Graz Centre of Electron Microscopy, Steyrergasse 17/III, 8010 Graz, Austria.|Institute for Electron Microscopy and Nanoanalysis, Graz University of Technology, Steyrergasse 17/III, 8010 Graz, Austria.
authors.forename: F
authors.initials: F
authors.lastname: Hofer
authors.affiliation: Graz Centre of Electron Microscopy, Steyrergasse 17/III, 8010 Graz, Austria.|Institute for Electron Microscopy and Nanoanalysis, Graz University of Technology, Steyrergasse 17/III, 8010 Graz, Austria.
authors.forename: G
authors.initials: G
authors.lastname: Kothleitner