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Atomic-scale observation of β′ and LPSO phase in Mg–Y–Ni alloy by HAADF-STEM

Published online by Cambridge University Press:  03 May 2019

Liping Yu ,
Xia Chen ,
Shaohan Wang  and
Bin Chen Open the ORCID record for Bin Chen [Opens in a new window]
Liping Yu
Affiliation:
The State Key Laboratory of Refractories and Metallurgy, Wuhan University of Science and Technology, Wuhan 430081, China
Xia Chen*
Affiliation:
The State Key Laboratory of Refractories and Metallurgy, Wuhan University of Science and Technology, Wuhan 430081, China
Shaohan Wang
Affiliation:
Frontier Research Center for Materials Structure, Shanghai Jiao Tong University, Shanghai 200240, China
Bin Chen*
Affiliation:
Frontier Research Center for Materials Structure, Shanghai Jiao Tong University, Shanghai 200240, China
*
a)Address all correspondence to these authors. e-mail: chenxiaocy@wust.edu.cn
b)e-mail: steelboy@sjtu.edu.cn
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Abstract

This paper reports on an atomic-scale investigation into the β′ precipitates and the long-period stacking ordered phase (LPSO) in Mg–5Y–2.5Ni–0.5Zr (at.%) alloy, using Cs-corrected high angle annular dark field-scanning transmission electron microscopy (HAADF-STEM). The results displayed that the 18R-type and 14H-type LPSO phases coexisted in the as-cast and the solid solution states, and the 18R-type and 14H-type LPSO structures were thermal stable. After aging treatment, the aging peak hardness reached 138 HV at 225 °C for 48 h. The significant increase in hardness was attributed to the formation of the metastable β′ phase. The lattice parameters of a and b axes for β′ phases are a = 0.65 nm, b = 2.20 nm, and c = 0.52 nm by HAADF-STEM. The interaction between the LPSO phase and the β′ can be found. The atomic-scale interactions between the LPSO and β′ phases are divided into two parts: under-aging and peak-aging conditions between the building blocks.

Keywords

magnesium alloyaging treatmentprecipitateslong-period stacking ordered (LPSO) phaseHAADF-STEM
Type
Article
Information
Journal of Materials Research , Volume 34 , Issue 20 , 28 October 2019 , pp. 3545 - 3553
Copyright
Copyright © Materials Research Society 2019 

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