| Particulate reinforced metal matrix composites possess several additional advantages such as light weigh high specific strength and stiffness great shear strength. So they are widely used in many general applications in spaceflight car fittings sports goods areas. According to the difference of the wild phase's formation, the composite's manufacturing method can be divided into traditional way and in situ way. The main disadvantages of the traditional way are the particles' conglomeration, bad compatibility between wild phase and matrix, low interfacial strength and so on. In situ way has overcome these disadvantages because the wild phase is formed in matrix. However, in situ way also has its disadvantages. It costs more than the traditional way and it is hard to control the process of the reaction. These disadvantages have led to some limitations of the composites' production and research. Therefore, the developing orientation of in situ composites is to search the means of lowering the cost and controlling the process of in situ reaction.There has been an increasing interest in the production of particulate reinforced aluminum matrix composites by the replacement reaction between low-cost oxides and Al. But most of the researches focus on the reaction of single oxide and Al to form wild phase Al2O3. These researches show that only CuO/Al reaction system can produce Al2O3 particles steadily. However, the reaction is very drastic and it belongs to blast reaction. The replacement reactions between other oxides and Al are very slow. It indicates that they don't accord with the dynamic conditions. So this research proposes a new idea to fabricate aluminum matrix composites by combining several oxides to react with Al at the same time. This idea overcomes the shortages of CuO/Al system and the other single oxide system. It extends in situ reaction system.In this paper, four reaction systems: CuO/Al, CuO+SiO2/Al, CuO+TiO2/Al, CuO+SiO2+TiO2/Al have been studied. The composites are fabricated by the four reaction systems. The microstructures hardness grinding performances and mechanical properties of the composites have been analyzed. This paper also discusses the influences of quality ratio and mixture of different oxides to the composites' properties. At the same time, the thermodynamic principles and principles of dynamics have been studied.The experimental results show that in situ reaction between several oxides and Al balances adiabatic temperature and controls the drastic reaction between CuO and Al. At the same time, this kind of in situ reaction also accelerates the other replacementreactions and makes them react till to the end. The microstructures of composites fabricated by this research are much smaller than the ones fabricated by single oxide. The quantity of CuAl2 phase is lessened largely and it doesn't form messy phase. The ceramic particles distribute in the aluminum matrix equably and strengthen the matrix.Under the same experimental conditions, the reaction is more thorough and the durative time of the reaction is also longer when the quantity ratio of CuO to the other oxides is 3:1 than when it is 2:1. In CuO+SiO2+TiO2/Al reaction system, the element Ti which is replaced in the reaction makes the microstructure of composite thin and the matrix strong. The mechanical properties of the composites fabricated by this reaction system are much finer than the ones fabricated by CuO+SiO2/Al and CuO+TiO2/Al reaction system. In CuO+TiO2/Al reaction system, the wild phase Al3Ti is very large and it is disadvantageous to the improvement of composites' properties.In situ reaction between oxide and Al is a diffusing process of reaction atoms. In this process, an integrated reaction membrane is engendered in the interface of oxide and Al firstly. Then the synthesis reaction holds on through the reaction atoms' diffusion. |
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