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用铸造法制备不同Zn含量的Mg-x Zn-2Gd合金,利用光学显微镜和扫描电镜对Mg-x Zn-2Gd合金的显微组织进行分析,采用室温拉伸实验对合金的力学性能进行测试。结果表明,Mg-Zn-Gd相沿晶界析出。随Zn含量的增加,铸态Mg-x Zn-2Gd合金的平均晶粒尺寸减小,第二相含量增多,屈服强度和抗拉强度升高。当Zn含量达到4wt%时,合金的力学性能达到峰值。经固溶处理后,第二相溶解,并随保温时间的延长,合金的显微硬度逐渐降低,在24 h时达到极小值。铸态Mg-4Zn-2Gd合金在430℃下进行固溶处理24 h后,屈服强度和抗拉强度降低,伸长率上升,为后续热挤压加工提供了良好的组织状态和力学性能。
The Mg-xZn-2Gd alloy with different Zn content was prepared by casting method. The microstructure of Mg-xZn-2Gd alloy was analyzed by optical microscope and scanning electron microscope. The mechanical properties of the alloy were tested by room temperature tensile test. The results show that the Mg-Zn-Gd phase precipitates along the grain boundaries. With the increase of Zn content, the average grain size of as-cast Mg-x Zn-2Gd alloy decreases, the content of second phase increases, and the yield strength and tensile strength increase. When the Zn content reaches 4wt%, the mechanical properties of the alloy peak. After solution treatment, the second phase dissolves, and with the extension of holding time, the microhardness of the alloy gradually decreases and reaches a minimum value at 24 h. When the as-cast Mg-4Zn-2Gd alloy was treated at 430 ℃ for 24 h, the yield strength and tensile strength of the as-cast Mg-4Zn-2Gd alloy decreased and the elongation increased, which provided good microstructure and mechanical properties for subsequent hot extrusion.