Structural changes of precipitates in an Mg-5at%Gd alloy studied by transmission electron microscopy

Masahiko Nishijima, Kenji Hiraga

Research output: Contribution to journalArticle

90 Citations (Scopus)

Abstract

Structural changes of precipitates in an Mg-5 at%Gd (Mg95Gd 5) alloy by aging at 200°C and 250°C have been studied by ordinary high-resolution transmission electron microscopy (HRTEM) and high-angle annular detector dark-field scanning transmission electron microscopy (HAADF-STEM). In the early stage of precipitation by aging at 200°C up to 5 h, a short-range ordered structure exists in Gd-enriched regions with an about 2 nm size, and nuclei of an Mg7Gd structure (β′ phase) occur in the short-range ordered structure by aging at 200°C for 5 h. The β′ phase with the Mg7Gd structure is formed as definite precipitates by aging at 200°C for 10h. The β′ precipitates are joined along the b-axis and form a plate-shape with a thickness of about 20 nm along the a-axis, and lengths of about 200 nm along the b-axis and 200 nm along the c-axis, and the connection of planar precipitates along the three directions, which are parallel to the [210]m-typed directions of the Mg-matrix, forms a two-dimensional cell structure, by top-aging at 200°C for 100h.

Original languageEnglish
Pages (from-to)10-15
Number of pages6
JournalMaterials Transactions
Volume48
Issue number1
DOIs
Publication statusPublished - 2007 Jan 1

Keywords

  • High-resolution transmission electron microscopy (HRTEM)
  • Magnesium alloy
  • Magnesium-gadolinium
  • Magnesium-rare earth alloy
  • Mg-Gd
  • Precipitate
  • Precipitation hardness

ASJC Scopus subject areas

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

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