| Aluminum matrix composites exhibit the characters of low density, high specificstrength and high specific modulus. These composites are being widely used in manyindustries such as aerospace, car industries, military, and electronics. Because of the lowstrength and hardness of Al, it is necessary to add reinforcements to improve themechanical property. In this paper, particulate reinforced aluminum matrix compositeswith different particle size of alumina were sintered under high pressure. Microstructureand properties of the composites were investigated compared with matrix sintered underan atmospheric pressure.Microstructure of aluminum composites was analyzed by Axiovert200MAT opticalmicroscope. The results showed that alumina particles mainly distributed on the grainboundary of the matrix. Hardness of the composites was studied with FM-700Vickershardness tester. The hardness of aluminum matrix composites sintered under high presswas higher than that of pure aluminum. The maximum hardness reached to64.85HV,about2.7times that of pure aluminum. INSTRON5982mechanical testing system testsshowed that compared with aluminum, the strength of the composites improved butpercentage elongation decreased. Fracture morphology was observed with the scanningelectron microscope. Fracture mechanism contained ductile fracture, brittle fracture anddisengagement of interfaces. The corrosion resistance was investigated by CHI660Aelectrochemical workstation. With the addition of the reinforcement, corrosion resistanceof the materials was improved to some extent.The aluminum matrix composites sintered were so dense that its relative densityreached over98%. Under a certain pressure, the higher the sintering temperature, thegreater the particle size of matrix. In addition, the hardness and tensile strength ofmaterials were improved while the fracture elongation decreased. Under the sametemperature, the higher the sintering pressure, the finer the grain size of matrixcomposites.Furthermore, hardness and tensile strength of materials increased. Whenfiner alumina particles were added to aluminum matrix, some of the grains were finer. This lead to a higher tensile strength and hardness while a lower elongation after fracture.Decreasing the pressure and increasing the sintering temperature could improvecorrosion resistance of the composites. When the particle size of reinforcements was3μm,the corrosion resistance of composites was higher than those added reinforcements of0.2μm。... |
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