(北京科技大学 铸造研究所， 北京 100083)
摘 要: 研究了喷射沉积Al20%Si及Al30%Si合金坯料的显微组织及形成机理。结果表明，两种合金的喷射沉积态组织为细小的团块状Si均匀地分布于基体α上，没有共晶组织出现。形成该组织特征的机理是由于在沉积阶段凝固过程中合金发生了离异共晶，在雾化阶段大的冷却速度下形成的大量Si相核心以及在沉积阶段相对较低的冷却速度为这一过程提供了动力学条件。通过自行设计的沉积阶段凝固的模拟实验，对这一机理进行了验证；另外，还对Si相的形态、尺寸进行了一定的研究。
关键字: 喷射沉积； 高硅铝合金； 离异共晶； 凝固
（Foundry Institute, University of Science and Technology Beijing, Beijing 100083, P.R.China）
Abstract:The microstructures of spray deposited Al20%Si and Al30%Si alloyswere investigated. The results show that the microstructures in these two alloys are featured by that fine block Si uniformly distributes on the α matrix and no conventional eutectic structure exists. The evolution mechanism of this structure peculiarity was presented. It is believed that the final microstructures of spray deposited hypereutectic alloys are the result of the divorce eutectic, which appears in the depositing solidification process. The large number of Si nuclei formed at high cooling rate in atomizing process and the low solidification rate in the depositing process are the dynamic factors for the evolution. In addition, a selfdesigned simulant solidification experiment verified this view. The morphology and the size of Si were also studied.
Key words: spray deposition; hypereutectic AlSi alloy; divorce eutectic; solidification
