Preparation,microstructure And Properties Of 6061Al/SiCp Composites

Particle reinforced aluminum matrix composites have excellent performance and have huge application potential in aerospace,automotive industry and other fields.However,the high strength and low toughness of particle-reinforced aluminum matrix composites have been restricting their development.Choosing the appropriate preparation method and the type of reinforcement are the two key points to solve this problem.In this paper,6061Al/SiCp composites were prepared by five methods: cold isostatic pressing+ extrusion,hot isostatic pressing,cold isostatic pressing + hot pressing sintering + extrusion,hot pressing sintering + extrusion,and canned extrusion.The composites were subjected to component analysis,microstructure observation,mechanical performance test,and fracture topography analysis to explore suitable preparation methods.And on this basis,the effect of heat treatment process on the structure and properties of the SiC and stainless steel particle hybrid reinforced aluminum matrix composites prepared by the canned extrusion method was systematically studied,and the strengthening mechanism of the reinforcing phase was explored.Comparing the dispersion effect of the mixed particles under different ball milling parameters,it was found that when the ball milling speed was 160 rpm and the ball milling time was 1 h,the mixed particles were basically uniformly distributed.XRD analysis results showed that the main components of the composite materials prepared by different methods are Al and SiC,and no other compounds were generated during the preparation process.The composites prepared by the five different molding methods all had a certain degree of defects.Among all of these methods,the composite prepared by canned extrusion had the most uniform distribution and the least pore defects.The results of mechanical properties showed that the composite prepared by canned extrusion had the best comprehensive mechanical properties,with an ultimate tensile strength of 317 MPa,an elongation of 3.25%,and a certain degree of plastic fracture characteristics on the fracture surface.In the hybrid reinforced aluminum matrix composite(HAMC),the addition of stainless steel particles increased the elongation of the material while retaining the strength.The different heat treatment parameters had obvious effects on the mechanical properties of composite materials.However,the stainless steel particles hardly affected the aging precipitation behavior of the 6061 Al alloy matrix in the composite.The tensile results showed that the composite had obtained the best comprehensive mechanical properties after aging at 180°C for 6 hours.At this situation,the ultimate tensile strength was 346 MPa and the elongation was 17.8%.The fracture type of SiCp single-reinforced aluminum matrix composite was brittle-ductile mixed fracture,and the fracture mechanism was the plastic deformation of the aluminum alloy matrix and the shedding of SiCp.For HAMC,the breakage of the stainless steel particles on the fracture surface showed that the load can be successfully transferred from the matrix to the stainless steel particles,and because stainless steel itself has good plasticity,it can alleviate the deformation incoordination between the aluminum alloy matrix and SiCp,which made the stress distribution in the HAMC more uniform,thereby improving the comprehensive mechanical properties of HAMC.