【作者】 郑晶；

【导师】 王智民； 张冀粤；

【作者基本信息】 西安理工大学 ， 材料加工工程， 2006， 硕士

【摘要】 本文采用压力熔渗和热挤压工艺制备了低膨胀、低密度Al-Si复合材料。确定了Al-Si复合材料压力熔渗和热挤压工艺参数；分析了压力熔渗和热挤压工艺对Al-Si复合材料成形性、组织和性能的影响；结合理论计算探索了Al-Si复合材料熔渗机理。本文的主要结论如下： 1．采用压力熔渗工艺可制备出综合性能优良的高硅含量的Al-Si复合材料。制备出的Al-Si复合材料热膨胀系数为8～10×10^-6／℃，密度为2.48g／cm³，抗压强度为217.5 MPa，延伸率为1.45％。 2．适当的提高熔渗温度和延长熔渗时间可改善Al-Si体系的润湿性能，有利于Al基体网络结构的形成。 3．压力熔渗工艺制备Al-Si复合材料中存在的大量共晶相和粗大条状Si颗粒严重影响材料力学性能。热挤压工艺可消除Al-Si复合材料中这些缺陷，改善材料的性能。 4．XRD分析结果中无氧化物相形成，这表明Al-Si复合材料的制备可无需气氛保护。 5．由于预制体中各成分的百分含量具有可调节性，因此采用压力熔渗法在预制体不会压缩变形的基础上可以自由的调节复合材料中硅增强相与铝基体之间的比例。 6．理论分析计算和实验研究结果表明，实际压渗压力大于理论压渗压力计算值，产生偏差的主要原因是计算模型理想化，且忽略了压力熔渗过程中预体制内气体阻力的作用。更多还原

【Abstract】 In the present paper, a new-style Al-Si composite, which possesses less density and lower expansion coefficient, was fabricated by the method of pressure infiltration combined with hot extrusion. The processing parameters of pressure infiltration and hot extrusion were confirmed. The influences of the processing parameters on the formability, the microstructure and the properties of Al-Si composites were discussed. The pressure infiltration mechanism was studied systematically by combining with the theoretic calculation. The main conclusions are presented as follows.1. High-performance Al-Si composite can be fabricated successfully by the method of pressure infiltration combined with hot extrusion. Its thermal expansion coefficient is 8～10×l0~6/℃, the density 2.48g/cm~3, the compresive strength 217.5 MPa, and the extensibility 1.45%.2. The wettability in the Al-Si system can be improved by elevating the infiltration temperature and elongating the infiltration time properly, which are helpful to form the network structure in the aluminum matrix.3. There are a large numbers of eutectic phases and some coarse, strip Si particles, which lead the mechnical property to worsen seriously, in Al-Si composite fabricated by single pressure infiltration. The eutectic phases and coarse, strip Si particles can be decreased by sequential hot extrusion, and the mechnical property of Al-Si composites can be improved remarkably.4. The XRD results show there is no metal oxides formed in Al-Si composites, and indicate that Al-Si composites can be prepared in no protective atmosphere.5. If the precast body is undeformed, the ratio between the Si reinforced particles and the aluminum matrix can be adjusted freely to obtain the high-performance Al-Si composite during the course of pressure infiltration6. The results of theoretical calculation and the experiments show that the actual infiltration pressure is larger than that of the theoretical calculation, which can be attributed to the simplification of the calculating model and the neglect of the air pressure in precast body in the course of pressure infiltration.更多还原