Effect of focal depth of haadf-stem imaging on the solute enriched layers in mg alloys

Takanori Kiguchi, Yohei Yamaguchi, Shunya Tashiro, Kazuhisa Sato, Toyohiko J. Konno

Research output: Contribution to journalArticle

7 Citations (Scopus)

Abstract

This study has found that the Z-contrast of aberration-corrected high-angle annular dark field-scanning transmission electron microscopy (HAADF-STEM) images of solute enriched layers in Mg-TM-RE (TM:Zn, RE:Y, Gd) alloys is sensitive to the imaging conditions: The defocus and the focal depth. Consequently, the depth position of solute enriched layers in the projected direction shows strong effect on the Z-contrast around each layer. The blurring of the Z-contrast is preferentially observed in both sides region along (0001)Mg basal planes. The boundary position between HCP- And FCC-type stacking sequence at edge regions does not change by defocus. The permissible defocus amount is comparable to the focal depth. The aberration-corrected HAADF-STEM has short focal depth less than 10 nm, so that it is critical for interpreting image contrast that the thin foil thickness and the depth position of the nano-size structure such as the solute enriched layers. In turn, it can be presumed, by the blurring of the Z-contrast, that the depth position of the solute enriched layers in the projected direction. Thus, the focal depth of aberration-corrected HAADF-STEM is quite sensitive to the depth position of solute enriched layers in the thin foil of specimens and the defocus of the electron probe, so that the imaging condition of aberration-corrected HAADF-STEM is critical in order to interpret correctly the Z-contrast of the images.

Original languageEnglish
Pages (from-to)1633-1638
Number of pages6
JournalMaterials Transactions
Volume56
Issue number10
DOIs
Publication statusPublished - 2015 Jan 1

Keywords

  • Channeling
  • Defocus
  • Focal depth
  • High-angle annular dark field-scanning transmission electron microscopy (haadf-stem)
  • Long-period stacking ordered structure (LPSO)
  • Magnesium alloy
  • Solute enriched layers

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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