In this study, Al-6Si-0.6Mg-0.6Cu-0.2Cr alloys were prepared with the combined addition of (Ce+Yb) using the traditional ingot metallurgy method. The synergistic effects of (Ce+Yb) modification on the microstructure, including α-Al dendrites and eutectic Si phases, as well as the mechanical properties of Al-6Si-0.6Mg-0.6Cu-0.2Cr cast alloys were systematically investigated using differential scanning calorimetry (DSC), optical microscopy (OM), scanning electron microscopy (SEM), energy diffraction spectrum (EDS), X-ray diffraction (XRD), transmission electron microscopy (TEM) and mechanical tests. The results showed that the combined addition of (Ce+Yb) refined the α-Al grains and modified eutectic Si phases, with the combined addition of 0.6 wt% (Ce+Yb) exhibiting the best impacts on them. The Al₁₁Ce₃ and Al₃Yb intermetallics were also obtained from the modification. Moreover, the Al₁₁Ce₃ and Al₃Yb intermetallics functioned as strengthening precipitates and the eutectic Si phases were further spheroidized in the alloy during heat-treatment processing with the combined addition of (Ce+Yb). Coupled with heat treatment, the alloy with 0.6 wt% (Ce+Yb) exhibited enhanced mechanical properties with microhardness, ultimate tensile strength, yield strength and elongation of 89.4%, 114.1%, 183.9% and 208.0%, respectively, which were higher than those of the alloy without (Ce+Yb) modification and heat treatment. Notably, when the alloy was modified with the combined addition of (Ce+Yb), its strength significantly improved, whereas the elongation was not reduced and inversely was increased.

本研究采用传统铸锭冶金法制备了Al-6Si-0.6Mg-0.6Cu-0.2Cr合金，同时添加(Ce+Yb)。(Ce+Yb) 变质对 Al-6Si-0.6Mg-0.6Cu-0.2Cr 铸造合金的显微组织（包括 α-Al 枝晶和共晶 Si 相）以及力学性能的协同效应进行了系统的研究。扫描量热法 (DSC)、光学显微镜 (OM)、扫描电子显微镜 (SEM)、能量衍射谱 (EDS)、X 射线衍射 (XRD)、透射电子显微镜 (TEM) 和机械测试。结果表明，(Ce+Yb)的联合添加细化了α-Al晶粒和改性共晶Si相，其中0.6wt%(Ce+Yb)的联合添加对它们的影响最好。Al ₁₁ Ce₃和 Al ₃ Yb 金属间化合物也从改性中获得。此外，Al ₁₁ Ce ₃和 Al ₃Yb 金属间化合物起到强化析出物的作用，在热处理过程中，合金中的共晶 Si 相进一步球化，同时添加了 (Ce+Yb)。与热处理相结合，0.6 wt% (Ce+Yb) 合金表现出增强的机械性能，显微硬度、极限抗拉强度、屈服强度和伸长率分别为 89.4%、114.1%、183.9% 和 208.0%，高于那些没有（Ce+Yb）变质和热处理的合金。值得注意的是，当合金通过(Ce+Yb)的组合添加进行改性时，其强度显着提高，而延伸率没有降低，反而增加。