| Titanium alloys have high specific strength and excellent corrosion resistance and are widely used in aerospace,weaponry,civil aviation,and industry.Titanium matrix composite materials(TMCs)have great potential for development,they have high specific strength,good high-temperature creep resistance of matrix materials,and have the advantages of ceramic reinforced phase such as high hardness,high specific rigidity,high specific elastic modulus and wear resistance.Making Ti6Al4V(TC4)alloy and titanium matrix composite materials into composite components not only saves cost and improves efficiency,but also can fully exert the excellent performance of each alloy.Therefore,this paper combines TC4 and TMC through diffusion connection technology,mainly analyzes the influence of temperature,pressure and time on the joint structure and mechanical properties,explores the basic conditions for the effect of various mechanisms,and establishes a interface evolution model to obtain the main conclusions as follow:(1)The effect of different processes on joint structure was studied.Too low process parameter conditions will lead to inadequate interface bonding,such as 850?,5MPa and 30 min.With the increase of process parameters(temperature,pressure and time),the tighter the interface,the wider the distribution of the dimple area and the more obvious the fracture toughness and fracture characteristics.(2)The effect of different processes on the mechanical properties of joints were studied.With the improvement of process parameters(temperature,pressure and time),the interface is getting closer and closer,the tensile,shear strength and joint hardness are gradually increasing,and the hardness values on both sides of the interface are gradually decreasing.However,when the process parameters are increased to 900?,8MPa or60 min,the increase in tensile strength,shear strength and joint hardness and the decrease in hardness values on both sides of the interface will decrease.Combined with the analysis of the joint morphology and the comparison of mechanical properties,the connection temperature of 900?,the pressure of 10 MPa and the time of 60 min were selected as the best combination of process parameters.The shear and tensile strength of the joint under this process condition reached 660 MPa and 1080 MPa,respectively,reaching 98.4%(671 MPa)and 97.3%(1110 MPa)of the strength of the titanium matrix composite material.(3)The mechanism of diffusion connection is studied,and the interface evolution model is established.In the early stage of pore closure,creep effect caused by pressure causes pores to shrink rapidly.In the middle and late period of pore closure,the creep stress decreases and the effect is weakened,and the interface diffusion plays a major role.The radius of the closed pore does not exceed 1 ?m.The surface diffusion mechanism mainly plays a role in the early stage,which can spheroidize the surface,and its diffusion distance limit does not exceed 4?m,which is conducive to other mechanisms in the later stage.In addition,for the titanium matrix composite material containing the reinforced phase,a reinforced phase migration mechanism is proposed,that is,the reinforced phase near the interface can migrate into the TC4 side under the action of high temperature and high pressure,thereby improving the strength of the interface. |
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