离心铸造自生Zn-Al-Si表面复合材料的组织与性能

摘要

采用热模金属型离心铸造Zn-27Al-5Si合金，获得了内层含大量初晶Si，外层有少量初晶Si，中层为细小共晶Si的表面复合材料。考察了复合材料的组织形貌和复合材料的形成过程，以及模温和转速对组织的影响。结果表明，随着模温的提高，初晶Si、共晶Si和基体组织变得粗大；随管模转速的增加，初晶Si在内侧富集层厚度减小，初晶Si面积比增大。复合材料的内层由于聚集了大量初晶Si而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Si的中层在断裂中比含块状初晶Si的内层经历了更多的塑性变形。%A new in-situ Zn-Al-Si surface composites was fabricated by using centrifugal casting. A high-volume fraction of primary Si particles in the inner layer was achieved. The formation mechanism of the gradient was discussed. The effect of technological parameters on the composites was investigated. Testing results show that the hardness and wear resistance of the composites depend mainly on the distribution of the primary silicon particles along radial direction. The inner layer of the composite shows the highest hardness and best wear properties. The fracture mode of the composites is primarily brittle. The inner layer of the composite exhibits more deformation than the inner layer during the fracture.