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

Time：2023-08-31　　　Hits：779

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

DOI: https://doi.org/10.1007/s41230-023-3027-0

Author: Ji-peng Li, De-gao Qiao, Shi-wen Dong, *Peng Peng, Xian-tao Yan, and Xu-dong Zhang

*Peng Peng

Ph. D., Professor. His research interests mainly focus on the solidification theory of nonferrous alloys (Sn-base, and TiAl alloys) during directional solidification, and advanced casting processes of structural superalloys (Ni-base alloys).

E-mail: pengp@lzu.edu.cn

Abstract: 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-Mg₂Zn₁₁) 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: λ₁=374.66V^-0.383, and λ₂=167.5V^-0.563 (λ₁ is the primary dendrite arm spacing, and λ₂ 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+Mg₂Zn₁₁) ternary eutectics in the Zn-9.5Al-3Mg-0.01Ce alloy will be replaced by ternary eutectics (Zn+Al+MgZn₂) when the growth rate is lower than 7.53 μm·s^-1.

Free full text: https://link.springer.com/article/10.1007/s41230-023-3027-0

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