A new strategy is proposed in this study to modify the microstructure of the Al-7Si alloy, which is widely employed in the aerospace and transportation sectors due to its lightweight, high specific strength, and specific modulus. The primary challenge of the Al-7Si alloy is its coarse microstructure, which undermines its mechanical properties. This research focuses on the effects of adding the AlCrNiTi master alloy and Ce to the Al-7Si alloy. The impact on both the microstructure evolution and the mechanical properties is examined, including analysis and discussion of the underlying mechanisms for refinement and strengthening. When the alloy was modified by 0.9 wt% of the AlCrNiTi master alloy and 0.1 wt% of Ce, there was a notable refinement of the α-Al phase, transforming it from a coarse dendritic structure to fine equiaxed grains. The addition of 0.9 wt% of the AlCrNiTi master alloy and 0.1 wt% of Ce can also reduce the secondary dendrite arm spacing (SDAS) to 5.9 μm. The eutectic Si phase underwent a significant transformation, changing from coarse flakes to fine granularity with rounded edges. Furthermore, CeSiNi, AlNi intermetallic compounds, and nanoscale AlCr particles were observed in the modified Al-7Si alloy. Tensile tests showed that the addition of the inoculant in the Al-7Si alloy enhanced the ultimate tensile strength (UTS) from 173 MPa to 211 MPa and increased the elongation (El) from 7.9% to 14.1%.

中文翻译：

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AlCrNiTi和Ce协同添加对亚共晶Al-7Si合金显微组织和力学性能的影响

本研究提出了一种新的策略来改变Al-7Si合金的微观结构，该合金因其轻质、高比强度和比模量而广泛应用于航空航天和交通运输领域。 Al-7Si 合金的主要挑战是其粗糙的微观结构，这会损害其机械性能。本研究重点研究在Al-7Si合金中添加AlCrNiTi中间合金和Ce的效果。研究了对微观结构演变和机械性能的影响，包括对细化和强化的基本机制的分析和讨论。当用0.9 wt%的AlCrNiTi中间合金和0.1 wt%的Ce对合金进行改性时，α-Al相显着细化，从粗大的枝晶结构转变为细小的等轴晶。添加0.9 wt%的AlCrNiTi中间合金和0.1 wt%的Ce也可以将二次枝晶臂间距（SDAS）减小至5.9 μm。共晶Si相经历了显着的转变，从粗片状转变为具有圆形边缘的细粒状。此外，在改性 Al-7Si 合金中还观察到 CeSiNi、AlNi 金属间化合物和纳米级 AlCr 颗粒。拉伸试验表明，在Al-7Si合金中添加孕育剂使极限抗拉强度（UTS）从173 MPa提高到211 MPa，延伸率（El）从7.9%提高到14.1%。