Due to their optimized mechanical properties under rapid solidification, Al–Cu–Si ultrafine eutectic alloys have been highlighted. The literature does not, however, establish correlations between thermal solidification parameters, mechanical properties, and microstructures of these alloys. Knowledge of cooling rates and growth rates and their associations with mechanical properties of Al–Cu–Si ultrafine eutectic alloys can guide the search for controlled and optimized processing conditions. Considering these issues, the present study analyzes the correlations between microstructures and mechanical properties of Al–15 wt% Cu–7 wt% Si, Al–22 wt% Cu–7 wt% Si, and Al–26 wt% Cu–7 wt% Si alloys produced by centrifugal casting in a copper mold. For this, Al–Cu–Si alloys’ samples with a stepped solidified form are subjected to microstructural assessment and mechanical properties characterization methods. The results show the existence of phases such as Al‐rich, Si, and Al₂Cu in different proportions for each cylindrical casting part. Eutectic bimodal structures have been observed. With the increase in either alloy Cu content or solidification cooling rate, increase in hardness is observed. However, the compressive strength is shown to be unaffected by the microstructural scale. These variations are discussed to guide the best balance of properties. Samples of the Al–26 wt% Cu–7 wt% Si alloy produced under eutectic growth rates between 0.8 and 1.2 mm s⁻¹ are those with superior properties.

中文翻译：

---

Al-Cu-Si超细共晶合金的力学性能，显微组织特征及其与凝固速率的关系

由于它们在快速凝固下具有最佳的机械性能，因此突出了Al-Cu-Si超细共晶合金。然而，文献没有建立这些合金的热凝固参数，机械性能和微观结构之间的相关性。冷却速率和生长速率及其与Al-Cu-Si超细共晶合金力学性能的关系的知识可以指导寻找受控和优化的加工条件。考虑到这些问题，本研究分析了Al–15 wt％Cu–7 wt％Si，Al–22 wt％Cu–7 wt％Si和Al–26 wt％Cu–7 wt的微观结构与力学性能之间的相关性。通过在铜模具中离心铸造生产的％Si合金。为了这，逐步凝固的Al-Cu-Si合金样品经过微结构评估和力学性能表征方法。结果表明存在诸如Al-rich，Si和Al等相每个圆柱形铸件以不同的比例添加₂ Cu。已经观察到共晶双峰结构。随着合金Cu含量或凝固冷却速率的增加，观察到硬度增加。但是，显示出抗压强度不受微观结构尺度的影响。讨论这些变化以指导性能的最佳平衡。具有优异性能的共晶生长速率为0.8至1.2 mm s ^-1的Al–26 wt％Cu–7 wt％Si合金样品。