| Composite materials based on aluminum alloy have excellent comprehensive properties,and have been widely used in aerospace,advanced weapons,transportation and other major fields,among which there are many series of aluminum alloys,such as 2000 series,5000 series,6000 series,7000 series and so on.At the same time,the aluminum matrix composites reinforced by silicon carbide whiskers(SiC_w)and silicon carbide particles(SiC_p)have been widely used in aerospace and military fields at home and abroad,which fully embodies its remarkable performance advantages and establishes its competitive situation in the material system.In this paper,the 5000 series aluminum matrix composites controlled by SiC_w and nano-SiC_p are deeply explored.With 5083 Al alloy powder as matrix,the composite material was prepared by powder metallurgy(PM),and the plastic deformation process of the composite material was carried out,and the microstructure and properties of the composites were discussed.The research contents and results of this paper are summarized as follows:(1)The sintering process of 5083 Al matrix composites reinforced by 20vol%SiC_w and2.4vol% nano-SiC_p was studied.The sintered materials were prepared by argon protection sintering after cold pressing.It was found that the hardness and density reached the peak when the sintering temperature was 700?,and the composites reinforced by 25vol%SiC_w,30vol%SiC_w and 2.4vol% nano-SiC_p could also be fully sintered when sintered at this temperature for 8 hours.(2)The effects of hot extrusion and hot extrusion parameters on 5083 Al matrix composites controlled by SiC_w and nano-SiC_p were studied.Hardness and density of the composite material after hot extrusion are 184 HV and 97.638%,respectively,which are increased by about 31.1% and 11.8% respectively compared with the sintered samples.The results show that the hardness and density of the extrusion ratio of 10: 1 are 167 HV and97.638%,and the compressive strength and fracture strain are 705 MPa and 24.475%,respectively.However,the hardness and density of the samples with extrusion ratio of 5: 1are 162 HV and 95.420%,and the compressive strength and fracture strain are 635 MPa and17.9%,respectively.By comparison,it is found that the hardness,density,compressive strength and fracture strain of hot extrusion die with extrusion ratio of 10: 1 are increased by3.1%,2.3%,11% and 37% respectively.(3)The effects of extrusion-annealing on the microstructure and properties of 5083 Al matrix composites reinforced by 20vol%SiC_w and 2.4vol% nano-SiC_p were studied.after annealing at 300?,400?,500?,3h and 6h,the tensile strength of extrusion mainly depends on the annealing time,while the elongation after fracture mainly depends on the annealing temperature.with the increase of annealing temperature and annealing time,its mechanical properties are getting better and better.After annealing at 500?×6h,the tensile strength has no obvious change,but the elongation after fracture increases by 175%.(4)The properties of three kinds of 5083 aluminum matrix composites reinforced by20vol%SiC_w,25vol%SiC_w,30vol%SiC_w and 2.4vol%nano-SiC_p were studied.When the content of SiC_w is above 25vol%,the strength and plasticity of the materials decrease sharply.The microstructure and properties of the composites prepared by 20vol%SiC_w and nonmodal were also studied.the results show that the difference between them lies in that the preparation of tri-modal structure can effectively control the plasticity of the composites,and the elongation and fracture strain of the composites with tri-modal structure are increased by about 18.2% and 9.4% respectively compared with those with non-modal structure.In this paper,SiC_w and nano-SiC_p are innovatively mixed to control the microstructure and properties of aluminum matrix composites.With high magnesium alloy(5083Al)as the matrix,5083 Al matrix composites are prepared by the process route of ball milling composite powder-press forming-argon protection sintering-hot extrusion-annealing treatment,which realizes the effective control of various process parameters and properties in powder metallurgy process. |
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