Hot Deformation Behavior And Microstructure And Mechanical Properties Of Copper Containing Titanium Alloy Sheet

Titanium alloys can be used to replace human bones due to its the great comprehensive mechanical properties and biocompatibility.However,the ordinary titanium alloy does not have antibacterial properties,implanted in the human body is likely to cause bacterial infection and failure of surgery.So the development of a new type of titanium alloy with antibacterial capacity has become the current hot spots.Cu element because of its excellent antibacterial properties,the use of a long time and low cost advantages has been widely used.In this paper,Ti-6Al-4V-5Cu alloy and Ti-15Mo-5Cu alloy were selected as the research object.These two kinds of alloy ingots were prepared smelting in ISM.Then to explore their hot deformation behavior and sheet properties.The results show that the as-cast microstructure of Ti-6Al-4V-5Cu alloy is Widmannstatten structure,and the as-cast Ti-15Mo-5Cu alloy is a single β-equiaxed structure.When the temperature is from 800℃ to 900 ℃ and the strain rate is 0.01s-1~1s-1,the deformation parameters on the two alloys have great influence during the hot deformation process.When the deformation rate is constant,the deformation temperature increases while the peak stress becomes smaller.When the deformation temperature is constant,the deformation rate become faster,the peak stress.Ti-6Al-4V-5Cu alloy has a thermal activation energy of 203.55 KJ / mol,while the raise together.Activation energy of Ti-15Mo-5Cu alloy is only 143.98KJ/mol,The dynamic recrystallization capacity of the Ti-15Mo-5Cu alloy is stronger.According to the deformation structure of the two alloys,it can be seen that when the dynamic recrystallization does not occur completely,the higher the deformation temperature,the finer the grain.When the deformation temperature is constant,the deformation rate become lower,while the grain size become smaller.When the dynamic recrystallization is complete,the increase of deformation temperature and the decrease of deformation rate all contribute to the growth of grain.The hot deformation mechanism of Ti-6Al-4V-5Cu alloy is dislocation’s slip and climb.The continuous dynamic recrystallization process occurs as follows.As the degree of dynamic recrystallization increases,the α phase changes from lamellar to spherical.The hot deformation mechanism of Ti-15Mo-5Cu alloy is grain boundary slip.Discontinuous dynamic recrystallization process is as follows.First of all,the grain boundary of the “bow” due to the crystal deformation is not uniform.Then the dislocation subgrain boundary and the grain boundary protrusion are directly nucleated to form new grains.After aging treatment of the hot deformedsample,it can be found that the alloy produces Ti2 Cu phase,and the Cu element mainly distributes the remaining β phase and Ti2 Cu phase.The results of multi-step deformation experiments show that the grains in the two-pass deformation are smaller than those in the three-step deformation.The rolling process parameters were worked out,according to the experimental results of multi-pass thermal simulation.After that the machined and mechanical properties of the rolled sheet were tested.The results show that the Ti-6Al-4V-5Cu alloy is composed of α and β,and there is only a single β phase in Ti-15Mo-5Cu alloy.While the Cu element is mainly distributed in β-transformed structure.The tensile strength of Ti-6Al-4V-5Cu alloy is higher and the elastic modulus of Ti-15Mo-5Cu alloy is lower than that of Ti-6Al-4V-5Cu alloy.Ti-6Al-4V-5Cu alloy has the characteristics of microporous aggregation fracture and cleavage fracture,and the fracture mechanism of Ti-15Mo-5Cu alloy is cleavage fracture.