TY - JOUR
T1 - Atomic-scale investigation of precipitate phases in QE22 Mg alloy
AU - Zhao, Xiaojun
AU - Li, Zhiqiao
AU - Zhang, Aiping
AU - Hao, Longlong
AU - Chen, Houwen
AU - Nie, Jian
N1 - Funding Information:
HWC acknowledges the support from the National Key Research and Development Program of China ( No. 2021YFB03702101 ), National Natural Science Foundation of China ( Nos. 52071033, 52101150 ), Sichuan Science and Technology Program ( No. 2022YFG0287 ), Fundamental Research Funds for the Central Universities ( No. 2682021CX114 ), and Project on Function Development of Large-scale Instruments of Chongqing University ( No. gnkf2022017 ). JFN acknowledges the financial support from the Australian Research Council .
Publisher Copyright:
© 2023
PY - 2024/4/1
Y1 - 2024/4/1
N2 - Precipitation-hardenable commercial Mg alloy QE22 (Mg-2.5Ag-2.0Nd-0.7Zr, wt.%) has excellent mechanical properties, but precipitates in this alloy have not been well understood. In this work, precipitate phases γ'', γ, and δ formed during the isothermal ageing process at 150, 200, 250, and 300 °C have been characterized using atomic-resolution high-angle annular dark-field scanning transmission electron microscopy and atomic-scale energy-dispersive X-ray spectroscopy. The morphology, crystal structure, and orientation relationship of these precipitate phases have been determined. Domain boundaries usually exist in a single γ particle, which can be characterized by a separation vector of [11¯01]α. The δ phase forms in situ from its precursor γ phase, consequently leading to the formation of three different variants within a single δ particle. The nucleation of the δ phase is strongly related to the domain boundaries of the γ phase. The formation of the γ phase may be promoted by its precursor γ'' phase. The similarities in atomic structures of the γ'', γ, and δ phases are described and discussed, indicating that transformations between these precipitate phases can be accomplished through the diffusion of added alloying elements.
AB - Precipitation-hardenable commercial Mg alloy QE22 (Mg-2.5Ag-2.0Nd-0.7Zr, wt.%) has excellent mechanical properties, but precipitates in this alloy have not been well understood. In this work, precipitate phases γ'', γ, and δ formed during the isothermal ageing process at 150, 200, 250, and 300 °C have been characterized using atomic-resolution high-angle annular dark-field scanning transmission electron microscopy and atomic-scale energy-dispersive X-ray spectroscopy. The morphology, crystal structure, and orientation relationship of these precipitate phases have been determined. Domain boundaries usually exist in a single γ particle, which can be characterized by a separation vector of [11¯01]α. The δ phase forms in situ from its precursor γ phase, consequently leading to the formation of three different variants within a single δ particle. The nucleation of the δ phase is strongly related to the domain boundaries of the γ phase. The formation of the γ phase may be promoted by its precursor γ'' phase. The similarities in atomic structures of the γ'', γ, and δ phases are described and discussed, indicating that transformations between these precipitate phases can be accomplished through the diffusion of added alloying elements.
KW - Electron microscopy
KW - Magnesium alloy
KW - Phase identification
KW - Phase transformation
KW - Precipitation
UR - http://www.scopus.com/inward/record.url?scp=85178276672&partnerID=8YFLogxK
U2 - 10.1016/j.jmst.2023.07.070
DO - 10.1016/j.jmst.2023.07.070
M3 - Article
AN - SCOPUS:85178276672
SN - 1005-0302
VL - 177
SP - 114
EP - 127
JO - Journal of Materials Science and Technology
JF - Journal of Materials Science and Technology
ER -