| As the core material in the field of aviation and weapon equipment,Al-Cu-Mg aluminum alloy has always been a hotspot in improving its strength,hardness,ductility and intergranular corrosion resistance in service environment.Aluminum matrix composites based on Al-Cu-Mg alloy own the comprehensive properties that metal alloy have,which have great research potential.Based on the strengthening methods and principles of alloys and composites in review,this paper adjusted the Cu and simplify other contents in traditional2124 aluminum alloy with Zr?Sr and Ti alloying.Effects of solid solution on microstructure and properties of new Al-5.6Cu-1.7Mg-0.2Zr-0.1Sr-0.6Ti alloy were discussed.Based on the component,effect of Cu?Mg content(Cu was 5.6wt.%?4.4wt.%?6.5wt.%,Mg was 1.7wt.%?1.7wt.%?2.5wt.%respectively)in alloy and different aging system on microstructure and properties of Al-xCu-yMg-0.2Zr-0.1Sr-0.6Ti alloy have been studied.On the basis of this research,the composites were prepared by the matrix with excellent properties.The relationship between microstructure and mechanical properties of SiCwreinforced composites were preliminarily explored.Thus,the research in this paper not only provides theoretical basis and experimental reference for the development of high strength and toughness of Al-Cu-Mg alloys,but also provides technological support for promoting the wide application of Al-Cu-Mg based composites in life.The main accomplished work and the main results obtained were as follows:(1)Effects of 4 different solution systems(480?×2h+490?×2h,490?×2h+500?×2h,500?×2h+510?×2h,510?×2h+520?×2h)on microstructure and properties of Al-5.6Cu-1.7Mg-0.2Zr-0.1Sr-0.6Ti new alloy was studied.Results showed:As the solution temperature increased,the grain size in the alloy increased gradually.When the solution temperature was lower than 520?,the number and size of the insoluble phases in the alloy decreased with the increase of the solution temperature.When the solution system was 510?×2h+520?×2h,the insoluble phases in the alloy began to increase,and the alloy appeared slightly overburned,but the tensile strength was the highest,reaching 490.14MPa.The dislocationstrength and dislocation contribution value in the alloy decreased with the increase of solution temperature.Alloys reached peak aging in 12h under T6.The strength and elongation after break and the intergranular corrosion resistance under 490?×2h+500?×2h and 500?×2h+510?×2h solid solution system were both great,so 490?×2h+500?×2h and 500?×2h+510?×2h was the most suitable solution system for Al-5.6Cu-1.7Mg-0.2Zr-0.1Sr-0.6Ti.(2)The effect of components and three aging systems T6:185?×12h,T6I4:185?×4h(water quenching)+85?×120h,T6I6:185?×4h(water quenching)+85?×120h+165?×12h on the microstructure and properties of the Al-xCu-yMg-0.2Zr-0.1Sr-0.6Ti alloy under 500?×2h solid solution was investigated.The results demonstrated:When Cu/Mg ratio was 2.6 and the Cu content was 4.4 wt.%,the insoluble phases in the alloy was the smallest.When the Cu?Mg content increased with Cu/Mg=2.6 unchanged,the insoluble phases in the alloy became coarse as well as the grain size and the properties of the alloy were significantly reduced,which indicates that the Cu?Mg content in the alloy should not be too high.When Cu/Mg=3.3,compared with T6,the tensile strength of the alloy gradually increased under T6I4 and T6I6,but the the elongation after break almost unchanged,Under T6I6,the tensile strength and the intergranular corrosion resistance were great,the tensile strength reached 475.5MPa and the elongation after break was 19.8%.When Cu/Mg=2.6,T6I4 was the best for the alloy.Based on a slight increase in strength,the plasticity of the alloy increased by 66.18%?103.92%.However,T6I4 slightly reduced the intergranular corrosion resistance of the alloy.In addition,the increase of Cu?Mg content could increase the intergranular corrosion resistance of the alloy.(3)The effects of matrix composites properties with three groups reinforcements:pure SiCw?SiCw+SiO2?SiCw+SiO2+nm-Ti combined with Al-5.6Cu-1.7Mg-0.2Zr-0.1Sr-0.6Ti matrix which using liquid-phase extrusion casting under T6:185?×xh and T6I4:185?×xh(water quenching)+85?×64h were investigated.Research demonstrated:The pure SiCwreinforced composite had the best internal bonding with matrix,there are many black agglomerations inside the SiCw+SiO2composites.The introduction of SiO2 did not improve the dislocation strengthening of the composite,but nm-Ti could greatly increase the dislocation contribution and dislocation strengthening value of the composites.The T6 peak aging time of the composites were 1h.The introduction of SiO2greatly increased the hardness of the composites,but reduced the compression performance at room temperature,the hardness of SiCw+SiO2composites reached 350.37 HV at T6 peak aging.Under T6I4,the compressive properties of pure SiCwreinforced composites reached 1005.98 MPa,and the compressive strain was 7.29%,which were greatly exceed that of matrix alloys. |
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