Precipitation Behavior of Mg-7Gd-3Y-2Zn-0.5Zr Alloy during Isothermal Aging

Precipitate phases in an Mg-7Gd-3Y-2Zn-0.5Zr alloy aged isothermally at 240 °C were examined using high-resolution transmission electron microscopy (TEM) and high-angle annular dark-field scanning TEM. The two types of precipitation sequence that involve Mg-Gd and long period stacking ordered (LPSO)...

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Bibliographic Details
Published in:Materials 2021-04, Vol.14 (7), p.1737
Main Authors: Yuan, Jiawei, Li, Ting, Zhang, Kui, Li, Xinggang, Li, Yongjun, Ma, Minglong, Shi, Guoliang, Du, Zhiwei, Liu, Wei, Peng, Yonggang
Format: Article
Language:English
Subjects:
Aging
Aging (metallurgy)
Crystal structure
Diffusion coefficient
Ductility
Gadolinium
High resolution electron microscopy
Homogenization
Magnesium alloys
Magnesium base alloys
Microstructure
Morphology
Precipitates
Precipitation hardening
Transmission electron microscopy
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Summary:Precipitate phases in an Mg-7Gd-3Y-2Zn-0.5Zr alloy aged isothermally at 240 °C were examined using high-resolution transmission electron microscopy (TEM) and high-angle annular dark-field scanning TEM. The two types of precipitation sequence that involve Mg-Gd and long period stacking ordered (LPSO) type were found. The LPSO type sequence consisted of the precipitation of γ'', γ', 14H-LPSO/18R-LPSO. The Mg-Gd type precipitation sequence involved the formation of β'(b.c.o.) and β1(f.c.c.). The sequence, morphology, distribution, and crystal structure of these precipitates formed during isothermal aging were investigated. The results indicated that the priority precipitation of Mg-Gd and LPSO type sequences during aging can be affected by Nd, which has a higher diffusion coefficient than Gd and Y. The dislocation structures and strengthening mechanism were also discussed.
ISSN:1996-1944
1996-1944
DOI:10.3390/ma14071737