过共晶铝硅合金因其优良的耐热性而受到汽车领域的广泛关注，但随着材料服役环境的日益严苛，进 一 步 提 升 过 共 晶 铝 硅 合 金 综 合 性 能 至 关 重 要 。 针 对 过 共 晶 Al-14Si-xCu-1Ni-0.5Mg-0.5Mn-yRE 合 金 ( 简 称Al-14Si-xCu-1Ni-yRE 合金， x=2 、3 、4 ，y=0.1 、0.3 、0.5 ，质量分数， %) ，通过 X 射线衍射仪 (XRD) 、光学显微镜 (OM) 、扫描电子显微镜 (SEM) 、拉伸测试等表征手段研究了不同 Cu 含量和 RE(La+Ce 混合稀土 ) 含量对 T6 态合金微观组织及力学性能的影响规律。 结果表明，随着 Cu 含量的增加， Al-14Si-xCu-1Ni-0.5RE 合金中富 Cu 相 ( 如 Al 2 Cu 、AlCuNi 相等 ) 数量不断增多，特别是当 Cu 含量添加至 4% 时，合金中 甚 至 存 在 大 量 的 长 针 状 AlSiCuNiRE 相 ，从 而 割 裂 基 体 ，合 金 伸长 率 不断下降，无法满足实际应用需求。 当 Cu 含量为 3% 时， Al-14Si-3Cu-1Ni-0.5RE 合金表现出最佳力学性能,合金的室温抗拉强度为 348.2 MPa 、高温抗拉强度为 180.3 MPa 、室温伸长率为 1.91% 。 此外，随着 RE 含量的不断增加，Al-14Si-3Cu-1Ni-yRE 合金中共晶 Si 的变质效果有所优化， 但长针状富 RE 相也不断增多。 当 RE 含量为 0.3% 时，Al-14Si-3Cu-1Ni-0.3RE 合金的室温抗拉强度、高温抗拉强度和室温伸长率分别达到 354.3 MPa 、 185.5 MPa 和 2.1% .

Hypereutectic Al-Si alloys have received much attention in the automotive field due to their excellent heat resistance, but as the service environment of these materials becomes increasingly demanding, it is crucial to further improve the overall performance of hypereutectic Al-Si alloys. In this paper, the effects of different Cu contents and RE (La+Ce mixed rare earth) contents on the microstructures and mechanical properties of hypereutectic Al-14Si-xCu-1Ni-0.5Mg-0.5Mn-yRE alloys (referred to as Al-14Si-xCu-1Ni-yRE alloys; x=2, 3, 4 wt. %; y= 0.1, 0.3, 0.5 wt. %) in the T6 state were investigated via analytical methods, including XRD, OM, SEM, and tensile tests. The results show that the number of Cu-rich phases (e.g., Al 2 Cu and AlCuNi phases) in the Al-14Si-xCu-1Ni-0.5RE alloy increases with increasing Cu content. In particular, when the Cu content is increased to 4 wt. %, a large number of long needle-like AlSiCuNiRE precipitates even exist in the alloy, which split the matrix. The alloy elongation consequently decreases continuously, which cannot satisfy practical application requirements. When the Cu content is 3 wt. %, the Al-14Si-3Cu-1Ni-0.5RE alloy shows the best mechanical properties, the room temperature tensile strength of the alloy is 348.2 MPa, the high temperature tensile strength is 180.3 MPa, and the room temperature elongation is 1.91% . In addition, the metamorphic effect of eutectic Si in Al-14Si-3Cu-1Ni-yRE alloys is optimized with increasing RE content, but the amount of long needle-like RE-rich phase continues to increase. The room temperature tensile strength, high temperature tensile strength and room temperature elongation of the Al-14Si-3Cu-1Ni-0.3RE alloy reach 354.3 MPa, 185.5 MPa and 2.1%, respectively, when the RE content is 0.3 wt. %.