(上海交通大学 金属基复合材料国家重点实验室， 上海 200030)
摘 要: 采用热模金属型工艺， 离心铸造自生增强的Zn-27Al-6.3Mg-3.7Si合金复合材料。 研究结果表明： 该合金内层聚集大量块状初生Mg↓2Si、 少量块状初生Si， 中层不含初生Mg2Si和初生Si， 外层含少量初生Mg2Si和初生Si； Zn-27Al-6.3Mg-3.7Si合金在凝固过程中， 先后经历了初生Si和初生Mg↓2Si的析出、 富Al的固溶Zn相析出、 Mg-Zn化合物的析出， 以及发生三元或四元共晶反应； 初生Mg2Si和初生Si的位置、 数量和分布决定于其内浮速度和离心力场作用下的凝固速度；含有初生Mg2Si和初生Si的内层和外层比中层具有更高的硬度和耐磨性。
关键字: 离心铸造； Zn-27Al-Mg-Si 合金； 自生复合材料； Mg2Si； Si
（State Key Laboratory of Metal Matrix Composites,
Shanghai Jiaotong University, Shanghai 200030, China）
Abstract:In-situ composite of Zn-27Al-6.3Mg-3.7Si alloy was fabricated by centrifugal casting using the heated permanent mold. This kind of composite is consisted of three layers, inner layer segregates lots of blocky primary Mg2Si and a little blocky primary Si, middle layer contains no primary Mg2Si and primary Si, outer layer contains a little. Zn-27Al-6.3Mg-3.7Si alloy solidifies according to following steps: firstly, the precipitation of primary Si and primary Mg2Si, secondly, the precipitation of Zn-phase enriched by Al, thirdly, the precipitation of Mg-Zn compound, and lastly, the occurrence of ternary or quaternary eutectic reaction. The position, quantity and distribution of primary Mg2Si and primary Si are determined by solidification velocity under the effect of centrifugal force and their floating velocity inward. The inner and outer layer contained primary Mg2Si and primary Si exhibit much higher hardness and wear resistance than the middle layer.
Key words: centrifugal casting; Zn-27Al-Mg-Si alloy; in-situ composites; Mg2Si; Si
