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Precipitation in Mg–Nd–Y–Zr–Ca Alloy during Isothermal Aging: A Comprehensive Atomic‐Scaled Study by Means of HAADF‐STEM
Author(s) -
Zheng Jingxu,
Li Zhi,
Luo Zhongyuan,
Xu Xuesong,
Chen Bin
Publication year - 2017
Publication title -
advanced engineering materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.938
H-Index - 114
eISSN - 1527-2648
pISSN - 1438-1656
DOI - 10.1002/adem.201600244
Subject(s) - precipitation , nucleation , materials science , alloy , isothermal process , atomic units , grain boundary , crystallography , metallurgy , thermodynamics , microstructure , chemistry , physics , meteorology , quantum mechanics
This paper investigates into the precipitation behavior of Mg–2Nd–1Y–0.1Zr–0.1Ca (wt%) alloy during isothermal aging at 225°C, using atomic‐scale HAADF‐STEM. The precipitation sequence in Mg–Nd–Y–Zr–Ca is identified as follows: nucleation(β L a n d β H ) → needle‐like precipitates composed of β M , β′ T , and β C structures as repetitive units → β 1 → equilibrium β. From an engineering point of view, the atomic‐size precipitates that distribute uniformly have a significant strengthening effect. In addition, the present study discusses three findings concerning the novel structures observed in the alloy: two types of interaction between needle‐like precipitates are observed; the previously reported β″ structure is doubted according to the analysis of the defects characterized from [ 11 2 ¯ 0 ] Mg ; calcium is observed to be enriched in β1 precipitates and along grain boundaries.