Microstructure And Properties Of TC4-6 Wt.%Cu By Hot Pressing Sintering

Titanium alloy has high specific strength,has obvious advantages in corrosion resistance and heat resistance compared with common aluminum and steel,and has a wide range of temperature.It is an important emerging material in military,aerospace and aerospace fields at present.But the conductivity of titanium alloy is poor compared with steel.Copper has excellent electrical conductivity.Adding copper as an alloying element into titanium alloy will improve the electrical conductivity of titanium alloy,which is beneficial to the application of titanium alloy in electrical conductivity.Titanium alloy have a variety of alloy elements,including copper as fast eutectoid titanium elements in titanium alloy strengthening effect,part of the Cu elements can form solid solution with?-Ti,the alloys have the effect of solid solution strengthening,part will eutectoid reaction with titanium Ti₂Cu phase,eutectoid products can pass the precipitation strengthening further improve the mechanical properties of titanium alloy.It can improve the electrical conductivity without reducing the mechanical properties of titanium alloy,which provides the possibility for the application of titanium alloy in the field of electric power In this paper,TC4-6 wt.%Cu material was prepared by vacuum hot pressing sintering,and the influences of sintering temperature,holding time and other factors on the density,phase evolution(XRD),particle flow,element diffusion,mechanical properties and electrical conductivity of titanium alloy material were studied.Firstly,this paper used Commercial simulation software to simulate the hot-pressing sintering process of TC4-6 wt.%Cu alloy,and revealed the flow rule of powder particles.It was found that the area near the two ends of the upper head would form a high-density area under the direct action of pressure,while the area near the two ends of the lower head would form a low-density area due to the limitation of mold wall friction.The effects of sintering temperature,holding time and pressing pressure on the relative density of the center were studied and the effects of sintering process parameters on the relative density of sintered samples were simulated.The high-diameter ratios of 0.6,0.8,1,1.2 and 1.4 were set for simulation.The results showed that when the high-diameter ratio increased from 0.6 to 1.4,the sintered samples gradually expanded in the low-density areas on both sides,and the relative density distribution inside gradually became uneven,which provided a basis for the parameter selection of subsequent experiments.According to titanium copper phase diagram chose four sintering temperature(800?,850?,900?,950?,1000?),the study found that the sintering temperature on the material has a significant influence on the relative density,copper particles will dissolve when the sintering temperature of 950?,copper elements part exist in the form of solid solution,part exist in eutectoid products,no residual copper elements exist,the material relative density is98.0%,and the tensile strength can reach 943 MPa.At the same time,due to the occurrence of the Ti-Cu eutectoid reaction,the existence of the second phase compound around the?phase reduces the elongation of the material to 6.1%.In addition,the addition of Cu element will reduce the porosity of TC4,and the relative density of TC4 containing 6 wt.%Cu under the same sintering parameters will be 4.7%higher than that of Copper-free TC4.When the temperature is below 950?,the relative density of titanium alloy decreases somewhat,at the same time,there is residual presence in the reaction of copper particles.Due to the low density,the tensile property of the material decreased.When the temperature is 1000?,the grain will continue to grow,and the grain size is relatively large,and tensile strength up to 921 MPa.In conclusion,the sintering temperature at 950?can make the material compact and make the Cu element fully reacted,and the Ti₂Cu phase dispersion distribution can strengthen the titanium alloy matrix and achieve the optimal comprehensive mechanical performance.This research adopts the vacuum hot-pressing sintering method preparation of titanium alloy,can effectively improve the utilization rate of alloy materials and reduce the cost of materials.In addition,Cu alloy elements added will reduce the sintering state of TC4 porosity,under the same sintering parameters the relative density of TC4 containing 6 wt.%Cu was 4.7%higher than that of non-copper TC4,and the strength and hardness of TC4 were also improved.Under the same hot-pressing sintering process parameters,the conductivity of TC4-6 wt.%Cu material was improved by 20.5%compared with TC4,and the conductivity of titanium alloy was improved.