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Atomic-scale insights on the plate-shaped γ″ phase in Mg–Gd–Y–Ag–Zr alloy

Published online by Cambridge University Press:  13 July 2020

Zhenyang Liu Open the ORCID record for Zhenyang Liu [Opens in a new window] ,
Zongrui Pei ,
Bin Chen Open the ORCID record for Bin Chen [Opens in a new window]  and
X. Q. Zeng
Zhenyang Liu
Affiliation:
School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai200240, China National Engineering Research Center of Light Alloy Net Forming and State Key Laboratory of Metal Matrix Composite, Shanghai Jiao Tong University, Shanghai200240, China
Zongrui Pei
Affiliation:
Oak Ridge National Laboratory, Oak Ridge, Tennessee37831, USA
Bin Chen*
Affiliation:
School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai200240, China
X. Q. Zeng*
Affiliation:
School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai200240, China National Engineering Research Center of Light Alloy Net Forming and State Key Laboratory of Metal Matrix Composite, Shanghai Jiao Tong University, Shanghai200240, China
*
a)Address all correspondence to these authors. e-mail: steelboy@sjtu.edu.cn
b)e-mail: xqzeng@sjtu.edu.cn
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Abstract

The γ″ phase (hexagonal structure with space group ${ P\bar{6}}2{ m}$) plays an important role in the strengthening of Mg–Gd–Y–Ag–Zr alloy. In this study, Cs-corrected high-angle annular dark-field scanning transmission electron microscopy was applied to characterize the Mg–Gd–Y–Ag–Zr alloy in different conditions (as-cast, solution-treated, and isothermally aged at 200 °C). The nucleation, growing process, and transformation behavior of the plate-shaped γ″ phase were systematically investigated on the atomic scale. We found that the nucleation sites of the γ″ phase were separated by close-packed planes of the Mg matrix and the γ″ phase developed in two perpendicular directions of $\langle 10\bar{1}0 \rangle$ and ⟨0001⟩. The growing process of the γ″ phase on the atomic scale was captured. The γ″ phase was thermodynamically stable at room temperature, and no transformation behavior of the γ″ phase was observed up to 200 h during isothermal aging at 200 °C.

Keywords

Mgphase transformationscanning transmission electron microscopy (STEM)
Type
Article
Information
Journal of Materials Research , Volume 35 , Issue 14 , 28 July 2020 , pp. 1837 - 1845
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Copyright © Materials Research Society 2020

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