Process And Mechanical Properties Research Of TC4/GH4169 Functionally Graded Materials By Direct Laser Deposition

TC4 and GH4169 alloys have broad application prospects.With the development of technology,it is difficult for single material to meet the requirements of special environment.TC4 has good comprehensive mechanical and mechanical properties,such as high specific strength and good corrosion resistance,and it is widely used in spacecraft,biomedical,marine and so on.However,TC4 has defects such as poor high temperature resistance,poor wear resistance,and low hardness,which is difficult to apply in high temperature and wear condition.GH4169 alloy has high strength,good toughness and corrosion resistance in high temperature environments below 650 °C.However,GH4169 has lower specific strength and twice density that of TC4.Because there are some differences in thermal properties such as elastic modulus and thermal expansion coefficient,the direct combination of the two alloys will generate large stress,and the joint will generate cracks and other defects in the complex external environment and become weak links.The gradient combination of TC4 and GH4169 alloys can meet the high temperature-lightweight requirements of key components in key areas.In this paper,TC4/GH4169 composites with different GH4169 incorporation and gradient materials with certain transition forms were prepared by direct laser deposition.Explored the reasonable range of process parameters,analyzed its phase composition and evolution mechanism,investigated the mechanical properties under different compositions,and revealed the correlation mechanism between microstructure and mechanical properties.Specific research contents are as follows.(1)According to the different doping ratio TC4/GH4169 composite materials,the surface parameters and macroscopic morphology of the formed samples were used as indicators to explore the process parameters of different TC4/GH4169 scale samples.Reasonable range of process parameters was obtained.(2)TC4/GH4169 composites with different doping ratios were tested for XRD phase detection,element distribution detection and microstructure analysis.The changes of microhardness and friction and wear of composites with different compositions were analyzed.Combined with the microstructure,the mechanism of association between mechanical properties and microstructure was further revealed.(3)Preparation was carried out in two ways: TC4/GH4169 gradient transition connection and TC4/GH4169 direct connection.The fracture mechanism of TC4/GH4169 direct connection on the fracture at the bonding interface was analyzed.The above phenomenon was optimized by the gradient transition connection,and finally a well-formed gradient sample was obtained.In addition,the variation of the microstructure and gradient transition interface layer inside the gradient sample,the distribution of elements and phases and the influence mechanism on the mechanical properties were analyzed.