离心铸造Zn-Al-Mg-Si合金及其自生表面复合材料

The Centrifugally Cast Zn-Al-Mg-Si Alloys and Their In Situ Surface Composites

采用热模金属型工艺,离心铸造Zn-27Al-9.8Mg-5.2Si和Zn-27Al-6.3Mg-3.7Si合金,获得了内层聚集大量块状初生Mg2Si、少量初生Si,中层不含初生Mg2Si、Si,外层含有初生Mg2Si、Si的自生表面复合材料.考察了成分、模具温度、转速、变质处理对离心铸造Zn-Al-Mg-Si合金组织和结构的影响.结果表明,Zn-27Al-9.8Mg-5.2Si合金自生复合材料内、外层的厚度比Zn-27Al-6.3Mg-3.7Si的厚度厚,初生Mg2Si的数量更多;随着转速增加,Zn-Al-6.3Mg-3.7Si合金自生复合材料的内层厚度增加,外层厚度减少;Na盐变质能够细化晶粒和初生Mg2Si,使初生Mg2Si分布更均匀,使初生Si团球化.最后分析了复合材料的成形过程.

In situ three-layer surface composites of Zn-27Al-9.8Mg-5.2Si and Zn-27Al-6.3Mg-3.7Si alloys were obtained by centrifugal casting with preheated metal mould, which possesses the microstructures of accumulated lots of blocky primary Mg2Si and a litter blocky primary Si in inner layer, accumulated primary Mg2Si and primary Si in outer layer, and without primary Mg2Si and primary Si in middle layer. The effects of composition, mold temperature, rotating rate and modification on microstructures of centrifugally cast Zn-27Al-Mg-Si alloys were investigated. The results show that the inner and outer layers of Zn-27Al-9.8Mg-5.2Si alloy are respectively thicker than those of Zn-27Al-6.3Mg-3.7Si alloy and have more primary Mg2Si. During the centrifugal casting of Zn-27Al-6.3Mg-3.7Si alloy, with rotating rate increasing, the thickness of the inner layer increases and the outer layer becomes thinner and the addition of Na-salt can refine grain and primary Mg2Si, and make primary Mg2Si distribute more evenly and make primary Si nodular. Moreover, the forming process of composites was also analyzed.