High-temperature performance is a key factor to concern for the application of cast Al–Si alloys. The evolution of microstructures and mechanical properties of a multiphase Al–Si–Cu–Mg–Ni–Ce alloy during tension in a temperature range from 25 °C (ambient temperature) to 425 °C was investigated. The results show that the main strengthening precipitates of the alloy are θ′ and Q phases. They are stable at 25–250 °C, while dissolve rapidly above 250 °C during tension. The damage initiates and propagates in the form of cracking of brittle phases. The fracture mechanism transforms from quasi-cleavage to coexistence of quasi-cleavage and dimple as temperature increases. The Ce-bearing phase Al₂₀Ti₂Ce promotes the damage occurrence below 350 °C while hinders crack propagation at 425 °C. The ultimate tensile strength (UTS) and yield strength (YS) decrease as the tensile temperature increases. The decreasing rate of UTS can be divided into three stages which is associated with the decreasing rate of strengthening precipitates. An empirical constitutive equation is proposed to describe the relationship between UTS and tensile temperature. It provides a good estimation for both cast and wrought Al alloys and the predicted strengths are in good agreement with the experimental results.

高温性能是铸造铝硅合金应用的一个关键因素。研究了多相 Al-Si-Cu-Mg-Ni-Ce 合金在 25 °C（环境温度）至 425 °C 温度范围内拉伸期间微观结构和机械性能的演变。结果表明，合金的主要强化析出相为θ′相和Q相。它们在 25–250 °C 下是稳定的，而在拉伸过程中，在 250 °C 以上时会迅速溶解。损伤以脆性相开裂的形式开始和扩展。随着温度的升高，断裂机制由准解理转变为准解理与凹坑并存。含 Ce 相 Al ₂₀ Ti ₂Ce在350°C以下促进损伤发生，而在425°C时阻碍裂纹扩展。随着拉伸温度升高，极限拉伸强度 (UTS) 和屈服强度 (YS) 降低。UTS 的下降速度可以分为三个阶段，这与强化析出物的下降速度有关。提出了一个经验本构方程来描述 UTS 和拉伸温度之间的关系。它为铸造和锻造铝合金提供了一个很好的估计，并且预测的强度与实验结果非常一致。