Obtaining γ″ phase by addition of Mn in Mg-Gd-Y-Zn-Ni-Mn alloy: atomic-scale insights by scanning transmission electron microscopy

ABSTRACT

To develop γ″ phase (hexagonal structure with space group $\mathrm{P}\overline{6}2\mathrm{m}$) containing high strength Mg-Gd alloys at lower cost, Mn instead of Ag was added. The state-of-art scanning transmission electron microscopy was applied to characterise γ″ in solution-treated and aged Mg-Gd-Y-Zn-Ni-Mn alloys on the atomic scale. γ″ was not found in the solution-treated state but was captured to precipitate during aging. γ″ with nonuniform occupations of Gd and Y was observed. Different modes of interaction between γ″ and β′ are proposed. The formation of γ″ promoted by Mn was not accidental, suggesting the possibility to form plenty of γ″.

KEYWORDS:

• Mg alloys
• HAADF-STEM
• precipitation
• segregation
• atomic structure

Acknowledgements

The authors sincerely thank Dr. Reddy at Shanghai Jiao Tong University for his advice on revising the manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the National Natural Science Foundation of China [grant number 51825101] and the National Key Research and Development Program of China [grant number 2016YFB0701201].