镁合金通过元素添加可显著拓宽其性能边界与应用场景，但这一过程往往伴随多种潜在缺陷的引入。本研 究旨在深入剖析Mg-3.5Y-0.9Ca-0.6Zr 合金中组织缺陷的形成机制及其对力学性能的影响， 为优化合金性能提供理论 依据。通过合金铸锭熔炼制备、合金板材轧制加工，并综合运用金相组织观察、室温拉伸力学性能测试、能谱成分分析及 扫描电镜微观形貌表征等手段，系统开展铸态与轧态合金的组织性能研究。实验结果表明，合金中的缺陷主要为偏析和 孔洞，其中偏析是主导缺陷，导致晶粒不均、性能降低，铸态合金抗拉强度154MPa、屈服强度83MPa、伸长率5.1%。 轧 制后缺陷减少，性能提升，轧态合金抗拉强度276MPa、屈服强度105MPa、伸长率7.1%。

The addition of various elements to magnesium alloys has expanded their applications but has resulted in numerous defects. This study delves into the formation mechanism of microstructure defects in Mg-3.5Y-0.9Ca-0.6Zr alloys and their impacts on mechanical properties, aiming to optimize alloy performance. A systematic study on the microstructure and properties of the as-cast and as-rolled alloys was carried out through the preparation of alloys by melting and rolling and comprehensive methods such as metallographic structure observation, room-temperature tensile mechanical property testing, energy dispersive spectroscopy composition analysis, and scanning electron microscopy micromorphology characterization. The results indicate that segregation and holes are the main defects, with segregation being the key defect. This phenomenon causes nonuniformity in the grains and performance degradation. The as-cast alloy has a tensile strength of 154 MPa, yield strength of 83 MPa, and elongation of 5.1%. Rolling reduces defects and enhances performance, and the as-rolled alloy exhibits a tensile strength of 276 MPa, yield strength of 105 MPa, and elongation of 7.1%.