Analysis on phase selection and microstructure evolution in directionally solidified Zn-Al-Mg-Ce alloy

In the process of hot-dip Zn-Al-Mg alloy coating, the plating solution dissipates heat in the direction perpendicular to the steel plate, which is considered to be a process of directional solidification. To understand the relationship between microstructure and cooling rate of Zn-Al-Mg alloys, both...

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Bibliographic Details
Published in:China foundry 2023-07, Vol.20 (4), p.347-355
Main Authors: Li, Ji-peng, Qiao, De-gao, Dong, Shi-wen, Peng, Peng, Yan, Xian-tao, Zhang, Xu-dong
Format: Article
Language:English
Subjects:
Alloys
Analysis
Coatings
Engineering
Machines
Manufacturing
Materials Engineering
Metallic Materials
Natural selection
Processes
Research & Development
Specialty metals industry
Zinc compounds
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Summary:In the process of hot-dip Zn-Al-Mg alloy coating, the plating solution dissipates heat in the direction perpendicular to the steel plate, which is considered to be a process of directional solidification. To understand the relationship between microstructure and cooling rate of Zn-Al-Mg alloys, both the phase constitution and microstructure characteristic length scales of Zn-9.5Al-3Mg-0.01Ce (wt.%) alloy were investigated by the directional solidification experiments at different growth velocities ( V =40, 80, 160, 250 µm·s −1 ). The experimental results show that the microstructure of directionally solidified Zn-9.5Al-3Mg-0.01Ce alloy is composed of primary Al dendrites and (Zn-Al-Mg 2 Zn 11 ) ternary eutectics at the growth velocities ranging from 40 to 250 µm·s −1 . The primary Al dendrites are aligned regularly along the growth direction, accompanied with obvious secondary dendrites. The relationship between the microstructure length scale and the thermal parameters of solidification is obtained: λ 1 =374.66 V −0.383 , and λ 2 =167.5 V −0.563 ( λ 1 is the primary dendrite arm spacing, and λ 2 is the secondary dendrit arm spacing). In addition, through the interface response function (IRF) and the nucleation and constitutional undercooling (NCU), the phase selection of Zn-9.5Al-3Mg-0.01Ce is obtained: (Zn+Al+Mg 2 Zn 11 ) ternary eutectics in the Zn-9.5Al-3Mg-0.01Ce alloy will be replaced by ternary eutectics (Zn+Al+MgZn 2 ) when the growth rate is lower than 7.53 µm·s −1 .
ISSN:1672-6421
2365-9459
DOI:10.1007/s41230-023-3027-0