Fabrication of A356 composite reinforced with micro and nano Al2O3 particles by a developed compocasting method and study of its properties
Fabrication of A356 composite reinforced with micro and nano Al2O3 particles by a developed compocasting method and study of its properties
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DOI：
10.1016/j.jallcom.2011.08.105
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发表时间：
2012-01
影响因子：
6.2
通讯作者：
S. Sajjadi;M. T. Parizi;H. Ezatpour;A. Sedghi
中科院分区：
文献类型：
--
作者：
S. Sajjadi;M. T. Parizi;H. Ezatpour;A. Sedghi
铝/氧化铝复合材料由于其低密度和良好的机械强度而被用于汽车和航空航天工业。本研究采用堆肥法制备了微、纳米氧化铝增强铝基复合材料。不同重量分数的微（3,5和7.5重量）。%)和纳米（1、2、3和4wt）。用氩气向半固态的A356铝合金中注入氧化铝颗粒，用机械搅拌器分别以200、300和450rpm的转速进行搅拌。利用光学显微镜和扫描电镜对复合材料的微观结构进行了研究。测定了微纳复合材料的密度和硬度变化。显微组织研究结果表明，复合处理导致基体合金由枝晶组织向非枝晶组织转变。SEM显微图显示，al2o3纳米颗粒被硅共晶包围，并倾向于向枝晶间区域移动。在1、2和3wt时，它们均匀地分散在基质中。%纳米al2o3或3和5wt。同时，进一步增加Al2O3(4wt。%纳米al2o3和7.5wt。%微Al2O3)导致团聚。密度测量结果表明，复合材料的孔隙率随重量分数、搅拌速度的增加和粒径的减小而增加。硬度测试结果表明，复合材料的硬度随颗粒尺寸的减小和颗粒质量分数的增加而增大。
Aluminum/alumina composites are used in automotive and aerospace industries due to their low density and good mechanical strength. In this study, compocasting was used to fabricate aluminum–matrix composite reinforced with micro and nano-alumina particles. Different weight fractions of micro (3, 5 and 7.5wt.%) and nano (1, 2, 3 and 4wt.%) alumina particles were injected by argon gas into the semi-solid state A356 aluminum alloy and stirred by a mechanical stirrer with different speeds of 200, 300 and 450rpm. The microstructure of the composite samples was investigated by Optical and Scanning Electron Microscopy. Also, density and hardness variation of micro and nano composites were measured. The microstructure study results revealed that application of compocasting process led to a transformation of a dendritic to a nondendritic structure of the matrix alloy. The SEM micrographs revealed that Al2O3nano particles were surrounded by silicon eutectic and inclined to move toward inter-dendritic regions. They were dispersed uniformly in the matrix when 1, 2 and 3wt.% nano Al2O3or 3 and 5wt.% micro Al2O3was added, while, further increase in Al2O3(4wt.% nano Al2O3and 7.5wt.% micro Al2O3) led to agglomeration. The density measurements showed that the amount of porosity in the composites increased with increasing weight fraction and speed of stirring and decreasing particle size. The hardness results indicated that the hardness of the composites increased with decreasing size and increasing weight fraction of particles.