稀土元素含量对铸造高稀土镁合金组织与性能的影响

Effect of Rare Earth Element Content on Microstructure and Properties of Cast High Rare Earth Magnesium Alloy

摘要: 为探究稀土总含量对镁合金显微组织及室温拉伸力学性能的影响，本研究采用低压铸造工艺制备WE43、Mg-14Gd及Mg-20Gd三种不同稀土含量的镁合金，并对其进行热处理。通过光学显微镜(OM)、配备能谱仪(EDS)的扫描电子显微镜(SEM)及室温拉伸试验，系统分析合金在铸态与热处理后的显微组织特征及力学性能规律。结果表明：随着稀土含量增加，合金组织中第二相体积分数呈递增趋势；铸态下，Mg-14Gd合金综合力学性能最优，其屈服强度、抗拉强度及延伸率分别达165 MPa、220 MPa和2.8%；固溶处理后，Mg-20Gd合金表现出最高的屈服强度(183 MPa)与抗拉强度(265 MPa)，而Mg-14Gd合金延伸率显著提升至15.3%，为三种合金中最高。本研究可为稀土镁合金的成分优化及工程化应用提供理论参考。

Abstract: To investigate the influence of total rare earth content on the microstructure and room-temperature tensile mechanical properties of magnesium alloys, this study prepared three magnesium alloys with different rare earth contents, namely WE43, Mg-14Gd and Mg-20Gd, by low-pressure casting and subjected them to heat treatment. The microstructure characteristics and mechanical properties of the alloys in as-cast and heat-treated states were systematically analyzed by optical microscopy (OM), scanning electron microscopy (SEM) equipped with energy dispersive spectrometer (EDS), and room-temperature tensile tests. The results show that with the increase of rare earth content, the volume fraction of the second phase in the alloys increases. In the as-cast state, the Mg-14Gd alloy shows the best comprehensive mechanical properties, with yield strength of 165 MPa, ultimate tensile strength of 220 MPa and elongation of 2.8%. After solution treatment, the Mg-20Gd alloy exhibits the highest yield strength (183 MPa) and ultimate tensile strength (265 MPa), while the elongation of the Mg-14Gd alloy significantly increases to 15.3%, which is the highest among the three alloys. This study can provide theoretical references for the composition optimization and engineering application of rare earth magnesium alloys.