Precipitation sequence in the mggdy system investigated by HRTEM and HAADF-STEM

Yuuki Matsuoka, Kenji Matsuda, Katsumi Watanabe, Junya Nakamura, Williams Lefebvre, Daisuke Nakagawa, Seiji Saikawa, Susumu Ikeno

Research output: Contribution to journalArticle

15 Citations (Scopus)

Abstract

In this work, the early stage of precipitation have been investigated in a Mg2.9 at% Gd0.8 at% Y by high angle annular dark fieldscanning transmission electron microscopy (HAADF-STEM) and high resolution transmission electron microscopy (HRTEM). At the underaged condition, precipitates observed by HRTEM were classified as follows; mono-layer, a part of β, βA. By HAADF-STEM, zig-zag structure, small hexagonal network, and βA could be recognized. The small "super hexagons" are the first precipitates in this alloy. This structure, referred to as the pre β-phase, displays a short range similar to the one present in the D019 structure. This phase is formed during quenching and prevails over the zig-zag structure at the beginning of aging. The zig-zag contrast is one of the variations of this small hexagonal network or heterogeneous nucleation during aging. Finally, we concluded that the proposed precipitation sequence is as follows: SSSSpre β-phase having D019-SROβ-phaseβA-phase. The comparison of HRTEM, HAADF-STEM and simulated images have helped to clarify the meaning of HRTEM features.

Original languageEnglish
Pages (from-to)1051-1057
Number of pages7
JournalMaterials Transactions
Volume55
Issue number7
DOIs
Publication statusPublished - 2014

Keywords

  • Age-hardening
  • High angle annular dark field-scanning transmission electron microscopy (HAADF-STEM)
  • High resolution transmission electron microscopy (HRTEM)
  • Magnesiumgadoliniumyttrium alloys
  • Precipitation

ASJC Scopus subject areas

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

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