Study On Performance Of Short-Carbon-Fiber Reinforced Aluminum Matrix Composites

With the development of modern science and technology, the properties of material were required higher and higher. The practical application could not be met by homogenous material so that leaded to metallic matrix composites develop quickly. Carbon fiber reinforced aluminum matrix composites were attracted the wide attention due to their high specific strength and rigidity, high temperature function and dimensional stability.In this paper, short carbon fiber reinforced Al alloys composites were fabricated by vacuum stirring melt casting method. The microstructure and interface structure of the composites are observed and analyzed. The density, hardness and strength of the composites were measured, and the fracture morphology of the composites was observed. The thermal expansion performance of the composites was also measured, effect of mass fraction of carbon fiber, carbon fiber size and pretreatment process on the thermal expansion performance of composites were also discussed.The results showed that carbon fiber in aluminum matrix different position of upper, middle and bottom distribute uniformly. Carbon fiber and alloy bonded excellently, and serious interfacial reaction did not happen. By using electroless copper plating on carbon fiber surface, the problems of poor wettability and interfacial reaction between carbon fiber and alloy matrix was improved and avoided respectively. With the increasing of carbon fiber volume fraction, the hardness and elongation degraded continuously, the tensile strength and bending strength of the composites increased firstly and arrived a peak value then decreased, while the hardness increased continuously. With the increasing of carbon fiber size, the hardness value had not been changed obviously, while the tensile strength and bending strength of the composites increased firstly and arrived a peak value then decreased still. Results indicated that carbon fiber mass fraction with6%, the length of copper plating carbon fiber with2mm could made composite material acquire good mechanical property. The studies of thermal performance showed that CTE of composite was lower than unreinforced aluminum alloy. The CTE of Cf/Al composite was not the same with different matrix alloy. With the increasing of carbon fiber size and mass fraction, the CTE of Cf/Al composite had shown a gradual increasing trend. Pretreatment had some influence on CTE of composite. The CTE of aged pretreatment was higher than the CTE of annealed pretreatment. The experiment value of composites with different mass fraction after annealing treatment waved in the ROM model and the Turner model, matching well with the Kerner model.