(Y, Gd)H2 phase formation in as-cast Mg-6Gd-3Y-0.5Zr alloy

In this work, a new (Y, Gd)H 2 precipitate was identified and systematically investigated in the as-cast Mg-6Gd-3Y-0.5Zr alloy by XRD, SEM with EDS, TEM with EDS techniques and thermodynamics analysis. Results show that the as-cast alloy contains α-Mg, Mg 24 (Gd, Y) 5 , and (Y, Gd)H 2 phase. The (Y,...

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Bibliographic Details
Published in:China foundry 2021-05, Vol.18 (3), p.217-222
Main Authors: Wang, Fei, Fu, Bin-guo, Wang, Yu-feng, Dong, Tian-shun, Li, Guo-lu, Zhao, Xue-bo, Liu, Jin-hai, Zhang, Gui-xian
Format: Article
Language:English
Subjects:
Engineering
gd)h2 phase
formation mechanism
Machines
Manufacturing
Materials Engineering
Metallic Materials
mg-6gd-3y-0.5zr alloy
as-cast
microstructure
(y
Processes
Research & Development
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Summary:In this work, a new (Y, Gd)H 2 precipitate was identified and systematically investigated in the as-cast Mg-6Gd-3Y-0.5Zr alloy by XRD, SEM with EDS, TEM with EDS techniques and thermodynamics analysis. Results show that the as-cast alloy contains α-Mg, Mg 24 (Gd, Y) 5 , and (Y, Gd)H 2 phase. The (Y, Gd)H 2 phase usually forms near the eutectic phase Mg 24 (Gd, Y) 5 or in the α-Mg grains, displaying a rectangle-shape. The Mg 24 (Gd, Y) 5 and (Y, Gd)H 2 phases crystalize in bcc and fcc structure, respectively, and the (Y, Gd)H 2 phase has a semi-coherent relationship with α-Mg matrix. The thermodynamics calculation results reveal that the hydrogen dissolved in the melt leads to the formation of hydrides. It is also found that the (Y, Gd)H 2 hydride can form directly from the liquid phase during solidification. Additionally, it can precipitate by the decomposition of Mg 24 (Gd, Y) 5 phase due to absorbing hydrogen from the remaining melt.
ISSN:1672-6421
2365-9459
1672-6421
DOI:10.1007/s41230-021-1013-y