离心铸造Mg_2Si和Si自生增强锌基复合材料的组织与性能

MICROSTRUCTURE AND PROPERTIES OF IN SITU Zn MATRIX COMPOSITES REINFORCED BY Mg_2Si AND Si USING CENTRIFUGAL CASTING

采用热模金属型工艺,离心铸造Zn27Al9.8Mg5.2Si和Zn27Al6.3Mg3.7Si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和初生Si,外层含有初生Mg2Si和初生Si的自生锌基复合材料。离心铸造Zn27Al3.2Mg1.8Si合金,获得了不含初生Mg2Si和初生Si的单层材料。考察了复合材料的组织形貌,检测了复合材料的硬度和耐磨性,分析了复合材料的断裂模式。结果表明:复合材料的内层因聚集大量的初生Mg2Si和初生Si具有较高的硬度和较优的耐磨性。复合材料的断裂方式为脆性断裂,含共晶MgSi和共晶Si的中层在断裂中比含块状初生MgSi和初生Si的内层经历了更多的塑性变形。

In situ three-layer surface composites of Zn-27Al-9.8Mg-5.2Si and Zn-27Al-6.3Mg-3.7Si alloys were obtained by using preheated metal mould centrifugal casting. The surface composites possess the microstructure accumulating lots of blocky primary Mg2Si and a small amount of blocky primary Si in the inner layer, accumulating primary Mg2Si and primary Si in the outer layer, and without primary Mg2Si and primary Si in the middle layer. But only single layer material without primary Mg2Si and primary Si was obtained in centrifugally cast Zn-27Al-3.2Mg-1.8Si alloy. Microstructures of centrifugally cast Zn-27Al-Mg-Si alloys were investigated, The hardness, wearability and fracture mode of the composites were also analysed, The results show that the hardness and wear resistance of the composites depend mainly on the distribution of the primary Mg2Si and primary Si along the radial direction. The inner layer of the composite shows the highest hardness and best wear resistance. The fracture mode of the composite is primarily brittle. The middle layer of the composite exhibits more deformation than the inner layer during the fracture.