Tilt boundaries and associated solute segregation in a Mg–Gd alloy

Y. M. Zhu, M. Z. Bian, J. F. Nie

Research output: Contribution to journalArticleResearchpeer-review

Abstract

Microstructures of a Mg–Gd solid solution single phase alloy that has been compressed at room temperature and subsequently annealed have been examined by bright-field and high-angle annular dark-field scanning transmission electron microscopy. It is found that the deformed microstructure contains many nano-sized grains. These nanograins exhibit strong texture: most of them have their 〈12¯10〉 parallel to each other. A range of tilt boundaries are detected between these nanograins, and they can be produced by basal-plane tilt or prismatic-plane tilt about the 〈12¯10〉 axis. Crystallographic analysis indicates that some of these tilt boundaries can be regarded as being generated by impingements of 〈12¯10〉 co-zone variants of {101¯1},{101¯2} and {101¯3} primary twins or secondary or tertiary twins. Segregation of Gd atoms occurs in the tilt boundaries after annealing of the cold deformed sample. The larger size Gd atoms segregate preferentially to dilated atomic sites within, or adjacent to, each tilt boundary to reduce local elastic strain. Consequently, the segregated Gd atoms form a range of unique, chemically ordered patterns specific to tilt boundaries.

Original languageEnglish
Pages (from-to)505-518
Number of pages14
JournalActa Materialia
Volume127
DOIs
Publication statusPublished - 1 Apr 2017

Keywords

  • Mg alloys
  • Solute segregation
  • STEM
  • Tilt boundary
  • Twin

Cite this

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abstract = "Microstructures of a Mg–Gd solid solution single phase alloy that has been compressed at room temperature and subsequently annealed have been examined by bright-field and high-angle annular dark-field scanning transmission electron microscopy. It is found that the deformed microstructure contains many nano-sized grains. These nanograins exhibit strong texture: most of them have their 〈12¯10〉 parallel to each other. A range of tilt boundaries are detected between these nanograins, and they can be produced by basal-plane tilt or prismatic-plane tilt about the 〈12¯10〉 axis. Crystallographic analysis indicates that some of these tilt boundaries can be regarded as being generated by impingements of 〈12¯10〉 co-zone variants of {101¯1},{101¯2} and {101¯3} primary twins or secondary or tertiary twins. Segregation of Gd atoms occurs in the tilt boundaries after annealing of the cold deformed sample. The larger size Gd atoms segregate preferentially to dilated atomic sites within, or adjacent to, each tilt boundary to reduce local elastic strain. Consequently, the segregated Gd atoms form a range of unique, chemically ordered patterns specific to tilt boundaries.",
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Tilt boundaries and associated solute segregation in a Mg–Gd alloy. / Zhu, Y. M.; Bian, M. Z.; Nie, J. F.

In: Acta Materialia, Vol. 127, 01.04.2017, p. 505-518.

Research output: Contribution to journalArticleResearchpeer-review

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AB - Microstructures of a Mg–Gd solid solution single phase alloy that has been compressed at room temperature and subsequently annealed have been examined by bright-field and high-angle annular dark-field scanning transmission electron microscopy. It is found that the deformed microstructure contains many nano-sized grains. These nanograins exhibit strong texture: most of them have their 〈12¯10〉 parallel to each other. A range of tilt boundaries are detected between these nanograins, and they can be produced by basal-plane tilt or prismatic-plane tilt about the 〈12¯10〉 axis. Crystallographic analysis indicates that some of these tilt boundaries can be regarded as being generated by impingements of 〈12¯10〉 co-zone variants of {101¯1},{101¯2} and {101¯3} primary twins or secondary or tertiary twins. Segregation of Gd atoms occurs in the tilt boundaries after annealing of the cold deformed sample. The larger size Gd atoms segregate preferentially to dilated atomic sites within, or adjacent to, each tilt boundary to reduce local elastic strain. Consequently, the segregated Gd atoms form a range of unique, chemically ordered patterns specific to tilt boundaries.

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