Effects of Homogenization Treatment on Microstructure and Mechanical Properties of As-cast Mg-9Gd-3Y-2.2Zn-0.5Zr Alloy

ZOU Jinchao; LIU Yu; GUO Yu; ZHANG Miaomiao; ZHENG Yonglin; WANG Yanyan; GAO Xiangyu

doi:10.3969/j.issn.1674-6457.2026.09.004

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Journal of Netshape Forming Engineering ›› 2026, Vol. 18 ›› Issue (9) : 32-40. DOI: 10.3969/j.issn.1674-6457.2026.09.004

Light Alloy Forming

Effects of Homogenization Treatment on Microstructure and Mechanical Properties of As-cast Mg-9Gd-3Y-2.2Zn-0.5Zr Alloy

ZOU Jinchao¹, LIU Yu¹, GUO Yu², ZHANG Miaomiao¹, ZHENG Yonglin¹, WANG Yanyan³, GAO Xiangyu^1,*

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Abstract

The work aims to clarify the effects of homogenization temperature and holding time on the microstructure, second-phase evolution, and mechanical properties of the as-cast Mg-9Gd-3Y-2.2Zn-0.5Zr alloy. The homogenization temperature range of the alloy was determined by TG-DSC analysis, and homogenization treatments were carried out at 480 ℃, 500 ℃, and 520 ℃ for 4-20 h. Combined with OM, SEM, XRD, and mechanical property testing, the synergistic mechanism by which second-phase evolution and elemental diffusion affected the strength-ductility balance of the alloy during homogenization was revealed. The results showed that, during homogenization, the brittle Mg₅(Gd,Y,Zn) eutectic phase at grain boundaries gradually dissolved, while Gd, Y, and Zn atoms diffused into the grain interior and promoted the formation and evolution of the LPSO phase, causing the grains to gradually become equiaxed and more uniform. However, excessively high temperature or prolonged holding time could lead to grain coarsening and dissolution of the LPSO phase, thereby weakening its deformation-coordination and strengthening effects. After homogenization at 480 ℃ for 8 h, the alloy achieved a favorable strength-ductility balance; therefore, this condition could be identified as the preferred homogenization treatment for the as-cast Mg-9Gd-3Y-2.2Zn-0.5Zr alloy. Its elongation increased from 4.59% in the as-cast state to 8.1%, approximately 1.76 times that of the as-cast alloy, while the ultimate tensile strength remained at 186 MPa without a significant decrease. These findings indicate that appropriate homogenization treatment effectively improves the strength-ductility balance of the Mg-9Gd-3Y-2.2Zn-0.5Zr alloy through brittle-phase dissolution, elemental diffusion, and the rational distribution of the LPSO phase, providing experimental evidence and theoretical guidance for optimizing the homogenization treatment process and subsequent plastic deformation processing of this alloy.

Key words

Mg-Gd-Y-Zn-Zr alloy / homogenization treatment / LPSO phase / microstructural evolution / mechanical properties

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ZOU Jinchao, LIU Yu, GUO Yu, ZHANG Miaomiao, ZHENG Yonglin, WANG Yanyan, GAO Xiangyu. Effects of Homogenization Treatment on Microstructure and Mechanical Properties of As-cast Mg-9Gd-3Y-2.2Zn-0.5Zr Alloy[J]. Journal of Netshape Forming Engineering. 2026, 18(9): 32-40 https://doi.org/10.3969/j.issn.1674-6457.2026.09.004

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Funding

The National Natural Science Foundation of China (52404408); Joint Fund Project of the National Natural Science Foundation of China (U24A20119); Fundamental Research Program of Shanxi Province (202403021222208); Scientific Research Startup Fund Project of Taiyuan University of Science and Technology (20242039)