Study On The Preparation And Properties Of6066Al/SiC_p Composites

Abstract:In this paper,6066Al/SiCp compositeswere preparedin two different ways,that is, canned extrusion and direct hot extrusion.The optimum heat treatment process of6066Al/SiCp composite and the effects of minor amount of Mg on the microstructure and properties of6066Al/SiCp composites were studied,as well as the different preparation methods on the properties of6066Al/3SiCp/2Mg composites were studied by optical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), differential scanning calorimetry test (DSC), X-ray diffraction analysis (XRD), tensile test, friction and wear tests and other experimental methods. The conclusions were as follows:(1)The heat treatment parameters of6066Al/3SiCp/2Mg is:520℃/120min solid solution, water quench under room temperature,160℃/8h aging. The heat treatment parameters of6066Al/3SiCp is:510℃/100min solid solution, water quench under room temperature,160℃/9h aging.(2) The adding of Mg precipitates the formation of magnesium aluminatespinel (MgAl2O4) layer among6066Al/SiC interfaces, and the generated coarse interfaces can precipitate the reinforcement particles better embed into the matrix, which substantially enhances the composite’s mechanical properties;The tensile strength and the yield strength of6066Al/3SiCp/2Mg measured in this experiment have enhanced by17%,23%respectively, the coefficient of friction is0.470,and it is also of a better abrasion resistance, the main form of fracture is ductile fracture of the matrix. However, the bonding between6066Al/3SiCp composite and Al/SiC interfaces is simple mechanical integration of oxide films, whose main form of fracture is interfacial de-bonding between SiC particles and the matrix.(3)After hot rolling,the porosity and osteoporosis of thecompos-ites prepared by canned extrusion significantly reduced,and the density of the materialincreased,but the precipitationof Mg2Si is thi-ck,and shows primary band microstructure along the hot rolling direction, the strength of the materials decreased. (4) The strength of6066Al/3SiCp/2Mg composites prepared by different methods are very close,relativelyspeaking, thedistribution of SiC part-icles in composites prepared by hot extrusionis uniform,whose depleted and segregation zone is relatively small,and the materialis more ductile. There are many small dimplein the cross section,the main form of fracture is ductile fracture of the matrix. The results of friction and wear tests show that the sample of smaller mass wear and better wear resistance.(5) In the preparation of composites by direct hot extrusion, degreasing process plays a key role,improper control will cause cracking, bubbling phenomenon,and will generate carbidesdue to the remained adhesive agent. The remained adhesive agent seriously affect the mechanical properties of the composites.The6066Al/3SiCp/2Mg composite material extruded at420℃of a rough surface cracking, and the sample extruded at450℃of higher strength.(6) The worn mechanism of6066Al/SiCp composite is quite complicated, because it is the product combined by many worn mechanisms. In the preliminary stage, the main worn mechanism is abrasive wear. With the friction process,the worn mechanism is converted into oxidation wear and adhesive wear,and finally to delamination wear.