中文摘要：

采用近液相线半连续铸造技术制备A390合金坯料,对铸锭显微组织进行金相观察,采用图像分析软件Image-ProPlus计算晶粒尺寸,研究浇注温度从高于液相线（650℃）100℃至10℃范围内变化对A390合金初生硅尺寸形貌的影响。结果表明：近液相线半连续铸造时,较低的浇注温度以及较均匀的温度场有利于均匀形核,同时减小熔体中Si的浓度梯度,从而消除Si原子聚集成团的条件,抑制初生硅的生长;因此,仅控制近液相线半连续铸造的工艺参数即可改善A390合金半固态坯料中初生硅尺寸形貌,这是制备过共晶铝硅合金半固态坯料的简单、可行、高效和低成本的方法。

英文摘要：

The A390 alloy billets were prepared using the near-liquidus semi-continuous casting technology.The microstructures of billets were observed by metalloscopy.The grain size was calculated by the Image-Pro Plus software.The influence of pouring temperature from 100 ℃ to 10 ℃ above the liquidus（650 ℃） on the shape and size of primary silicon particles of A390 alloy were studied.The results show that lower temperature and more uniformly distributing temperature field in the melt during near-liquidus semi-continuous casting help to nucleation and decrease concentration gradient of Si,which eliminates the gathering process of Si atoms and restrains the anisotropic growth of primary Si particle.So,controlling the processing parameters of near-liquidus semi-continuous casting can improve the primary Si of A390 alloy semi-solid billets,which will be a simple,feasible and effective method to prepare the semi-solid billets of hypereutectic Al-Si alloys.