In the current study, a series of forty-two cast Al–Si–Cu–Mg -based alloys with additions of transition metals (V, Cr, Ni) and rare earth (RE) metals (La, Ce) were prepared and mechanically tested in the as-cast, T5, T6 and T7 heat treatment conditions. The microstructures were investigated using optical microscopy, scanning electron microscopy (SEM) and electron probe microanalysis (EPMA). The volume fraction, aspect ratio, and roundness of second phase constituents were determined by ImageJ analysis software. The microstructural observations show that the RE elements have a greater impact on the microstructure of cast alloys, resulting in the formation of new types of intermetallic phases containing RE, Al–Si–Cu–RE and Al–Ti–RE. With regard to the mechanical properties, it was found that the highest strength of the casting alloys was found with 0–0.2 wt% addition of Ce/La. However, the addition of more than 0.2 wt% induced a detrimental effect on the mechanical properties due to precipitation of a high volume fraction of insoluble intermetallic compounds containing RE. Excessive addition of RE elements leads to the formation of a coarse intermetallic compound along the grain boundary. Besides, RE elements have a marginal modification effect in terms of changing the morphology of the eutectic Si particles.

在目前的研究中，制备了一系列添加了过渡金属（V、Cr、Ni）和稀土（RE）金属（La、Ce）的 42 种铸造 Al-Si-Cu-Mg 基合金，并对其进行了机械加工。在铸态、T5、T6 和 T7 热处理条件下进行测试。使用光学显微镜、扫描电子显微镜 (SEM) 和电子探针微量分析 (EPMA) 研究微观结构。第二相成分的体积分数、纵横比和圆度由 ImageJ 分析软件确定。显微组织观察表明，稀土元素对铸造合金的微观结构有更大的影响，导致形成含有稀土、Al-Si-Cu-RE 和 Al-Ti-RE 的新型金属间相。关于机械性能，结果表明，添加 0-0.2 wt% 的 Ce/La 时铸造合金的强度最高。然而，由于高体积分数的含稀土的不溶性金属间化合物的沉淀，添加超过 0.2 wt% 会对机械性能产生不利影响。RE元素的过量添加导致沿晶界形成粗大的金属间化合物。此外，稀土元素在改变共晶硅颗粒的形态方面具有边际改性作用。RE元素的过量添加导致沿晶界形成粗大的金属间化合物。此外，稀土元素在改变共晶硅颗粒的形态方面具有边际改性作用。RE元素的过量添加导致沿晶界形成粗大的金属间化合物。此外，稀土元素在改变共晶硅颗粒的形态方面具有边际改性作用。