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一、前言 为了满足航空航天和汽车工业对材料高比强度、高比弹性及耐高温的需求,世界各国十分重视金属基复合材料的研究与开发。但大量的研究工作主要集中在纤维或颗粒单一增强的复合材料方面,而对纤维和颗粒混杂增强的金属基复合材料的研究却很少。 挤压铸造法制备金属基复合材料具有工艺简单可靠,有利于产品工业化生产等优点,国内外进行了很多研究工作。特别是Al_2O_3短纤维(含Al_2O_3 50～80％)增强的铝基复合材料已被应用在发动机活塞的生产上。石墨(Gr)是一种自润滑性很好的材料,它的密度低、使用温度范围宽,Gr/Al复合材料是一种很有发展前途的金属基复合材料。但在采用半固态法制备Gr/Al复合材料中,工艺控制难度较大,难以用于产品的工业化生产。并且Gr和Al基体的界面反应难以预料和控制。本研究采用挤压铸造工艺较好地解决了这个难题,利用了Al_2O_3短纤维和Gr各自结构和性能的特点,获得了组织和性能较为理想的铝基复合材料。 二、实验方法
I. Preface In order to meet the demand of high strength, high flexibility and high temperature resistance of the aerospace and automotive industries, all countries in the world attach great importance to the research and development of metal matrix composites. However, a large amount of research work mainly focuses on the composite materials with single fiber or particle reinforcement. However, there are few studies on the metal matrix composites reinforced with fibers and particles. Squeeze casting method for preparing metal matrix composites is simple and reliable, is conducive to the advantages of industrial products such as production, a lot of research work at home and abroad. In particular, aluminum-based composites reinforced with Al 2 O 3 short fibers (containing 50% to 80% Al 2 O 3) have been used in the production of engine pistons. Graphite (Gr) is a very self-lubricating material, its low density, wide temperature range, Gr / Al composite is a very promising metal matrix composites. However, in the preparation of Gr / Al composites by semi-solid method, the process control is difficult and difficult to use in the industrial production of the product. And the interfacial reaction between Gr and Al matrix is difficult to predict and control. In this study, the squeeze casting process to solve this problem is a good solution, the use of Al 2 O 3 short fibers and Gr each structure and properties of the characteristics and obtain the desired structure and properties of aluminum-based composites. Second, the experimental method