(北京科技大學(xué) 鑄造研究所， 北京 100083)
摘 要: 研究了噴射沉積Al20%Si及Al30%Si合金坯料的顯微組織及形成機(jī)理。結(jié)果表明，兩種合金的噴射沉積態(tài)組織為細(xì)小的團(tuán)塊狀Si均勻地分布于基體α上，沒有共晶組織出現(xiàn)。形成該組織特征的機(jī)理是由于在沉積階段凝固過程中合金發(fā)生了離異共晶，在霧化階段大的冷卻速度下形成的大量Si相核心以及在沉積階段相對(duì)較低的冷卻速度為這一過程提供了動(dòng)力學(xué)條件。通過自行設(shè)計(jì)的沉積階段凝固的模擬實(shí)驗(yàn)，對(duì)這一機(jī)理進(jìn)行了驗(yàn)證；另外，還對(duì)Si相的形態(tài)、尺寸進(jìn)行了一定的研究。
關(guān)鍵字: 噴射沉積； 高硅鋁合金； 離異共晶； 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
