Research ArticleMATERIALS SCIENCE

High density of genuine growth twins in electrodeposited aluminum

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Science Advances  18 Oct 2019:
Vol. 5, no. 10, eaax3894
DOI: 10.1126/sciadv.aax3894
  • Fig. 1 Electron microscopy investigations of the electrodeposited Al layer.

    (A) SEM image of a cross section through the Al deposit, revealing micrometer-sized grains containing a high density of twins. The bright line at the bottom indicates the interface between the deposited Al film and the substrate (Ag paste). (B) TEM image taken from a top-view specimen, revealing a high density of twins. (C) This is also confirmed in the TEM image taken from a cross-sectional specimen.

  • Fig. 2 TEM investigation of the electrodeposited Al specimen (top view).

    (A) Diffraction pattern ([110] orientation) taken from a twinned grain. The mirror plane (blue line) and a twin reflection (subscript T) are marked. (B) Color-coded overlay of dark-field images generated using the reflections marked green (200) and red (200T) in (A). (C) High-resolution TEM image showing the atomic structure of a twin boundary.

  • Fig. 3 Construction of supercells used for simulations.

    (A) Hexagonal supercell (1 × 1), constructed by stacking 40 (111) planes. In this image, the supercell is repeated normal to the [111] direction to better show the marked defect structure. (B) Simulation cell used in the twin propagation calculations, with the twin position Ag (bottom; gray) and Al (top; blue) marked. Images were generated using VESTA (53).

  • Fig. 4 Effect of (surface) adsorbates, Hads and Clads, on Al twinning, according to DFT calculations.

    (A) Surface models used to study the effects of adsorption. (B) The difference between total energies of twinned and pristine Al(111) in the case of no adsorbate on the surface and when the surface is saturated with 1 ml of Hads or Clads. The position of the stacking fault is varied with respect to the surface layer.

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/5/10/eaax3894/DC1

    Fig. S1. Cyclic voltammogram recorded on Ag substrate.

    Fig. S2. Potential time curves obtained at different current densities on Ag substrates in AlCl3-[EMIm]Cl ionic liquid at 85°C.

    Fig. S3. SEM image of Al deposit formed at a current density of −10 mA cm−2.

    Fig. S4. SEM images of Al interface and screen-printed Ag substrate.

    Fig. S5. Supercell used in bulk defect calculations and different combinations of twinning.

    Fig. S6. Nanoindentation on cross sections obtained on electrodeposited Al sample and a commercial high-purity Al foil.

    Table S1. Average composition measured by EDS from the top-view TEM sample.

    Table S2. Calculated lattice constants, cohesive energies, twin formation energy, and intrinsic stacking fault energy.

    References (4952)

  • Supplementary Materials

    This PDF file includes:

    • Fig. S1. Cyclic voltammogram recorded on Ag substrate.
    • Fig. S2. Potential time curves obtained at different current densities on Ag substrates in AlCl3-EMImCl ionic liquid at 85°C.
    • Fig. S3. SEM image of Al deposit formed at a current density of −10 mA cm−2.
    • Fig. S4. SEM images of Al interface and screen-printed Ag substrate.
    • Fig. S5. Supercell used in bulk defect calculations and different combinations of twinning.
    • Fig. S6. Nanoindentation on cross sections obtained on electrodeposited Al sample and a commercial high-purity Al foil.
    • Table S1. Average composition measured by EDS from the top-view TEM sample.
    • Table S2. Calculated lattice constants, cohesive energies, twin formation energy, and intrinsic stacking fault energy.
    • References (4952)

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