The performances of magnesium alloys remain insufficient to further enhance the application potential of ultralight magnesium alloys. In this work, a Mg-8Li-3Y-2Zn alloy was prepared through vacuum melting and subsequent heat treatment at 300, 450, and 500 °C. The material properties of the resulting samples were assessed through microstructural observation, tensile testing, electrical conductivity measurements, and electromagnetic shielding effectiveness (EMI-SE) testing. The influence of the Mg-8Li-3Y-2Zn alloy microstructure on its mechanical and electromagnetic shielding properties in different states was investigated. It was found that the as-cast alloy contains α-Mg, β-Li, MgZnY, and MgZnY phases. Following heat treatment at 500℃ (HT500), the block α-Mg phase transformed fine needle-shapes, its tensile strength increased to 263.7 MPa, and its elongation reached 45.3%. The mechanical properties of the alloy were significantly improved by the synergistic effects imparted by the needle-shaped α-Mg phase, solid solution strengthening, and precipitation strengthening. The addition of Y and Zn improved the EMI-SE of Mg-8Li-1Zn alloy, wherein the HT500 sample exhibits the highest SE, maintaining a value of 106.7–76.9 dB in the frequency range of 30–4500 MHz; this performance has rarely been reported for electromagnetically shielded alloys. This effect was mainly attributed to the multiple reflections of electromagnetic waves caused by the severe impedance mismatch of the abundant phase boundaries, which were in turn provided by the dual-phase (α/β) and secondary phases. Furthermore, the presence of nano-precipitation was also believed to enhance the absorption of electromagnetic waves.

中文翻译：

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热处理后Mg-Li-Y-Zn合金机械和电磁屏蔽性能的协同改善

镁合金的性能仍不足以进一步增强超轻镁合金的应用潜力。在这项工作中，通过真空熔炼和随后在 300、450 和 500 °C 的热处理制备了 Mg-8Li-3Y-2Zn 合金。通过微观结构观察、拉伸测试、电导率测量和电磁屏蔽效能 (EMI-SE) 测试来评估所得样品的材料特性。研究了不同状态下Mg-8Li-3Y-2Zn合金显微组织对其机械和电磁屏蔽性能的影响。结果发现，铸态合金含有α-Mg、β-Li、MgZnY和MgZnY相。经过500℃（HT500）热处理后，块状α-Mg相转变为细针状，抗拉强度提高到263.7 MPa，伸长率达到45.3%。在针状α-Mg相、固溶强化和沉淀强化的协同作用下，合金的力学性能得到显着提高。 Y和Zn的添加改善了Mg-8Li-1Zn合金的EMI-SE，其中HT500样品表现出最高的SE，在30-4500 MHz频率范围内保持在106.7-76.9 dB的值；电磁屏蔽合金的这种性能很少有报道。这种效应主要归因于丰富的相边界的严重阻抗失配引起的电磁波的多次反射，而这些阻抗失配又是由双相（α/β）和二次相提供的。此外，纳米沉淀的存在也被认为可以增强电磁波的吸收。