Influence Of V Element On Microstructure And Properties Of Ti-Zr-V Alloy Produced By Laser Additive Manufacturing

Titanium alloys are widely used in aerospace,marine,chemical,medical and other fields due to their high specific strength,excellent corrosion resistance,high temperature mechanical properties,and good weldability.However,due to the high specific yield stress and low thermal conductivity of titanium alloys,it is a typical difficult to process alloy system.The laser additive manufacturing technology can realize the mold-free,high-density and near-net shape of highperformance complex parts,and has the advantages of high flexibility,short cycle,controllability and control integration,etc.,which is to meet the current titanium alloy processing and molding.Good choice.At present,the research on laser additive manufacturing at home and abroad mainly focuses on the control of forming equipment,related software and process parameters,while the research on materials is relatively weak.Therefore,it is extremely urgent to develop a new alloy material that is suitable for both the characteristics of the laser additive manufacturing process and the excellent performance.Based on the Ti-Zr binary alloy,the design concept of "cluster + connected atom" model is used to add five different V contents to the isomorphous element V of β-Ti by means of alloying.Alloy composition.Using modern microscopic analysis techniques such as XRD,SEM and EPMA,the system analyzed the solidification microstructure of Ti-Zr-V alloy and its evolution with V content under non-equilibrium solidification conditions.Based on the microstructure analysis of Ti-Zr-V alloy fabricated by laser additive,the intrinsic relationship between the formability,mechanical properties,corrosion resistance and V content of the alloy was further discussed.The results show that the phase of Ti-Zr-V alloy fabricated by laser additive is β-Ti single phase,and its microstructure is mainly composed of irregular equiaxed crystals and columnar crystals in the middle and lower parts.With the increase of V content,the crystal grains of columnar crystals and irregular equiaxed grains are obviously refined,and the degree of intragranular segregation of the alloy is also increased.The study of its formability shows that as the V content increases,the fluidity will deteriorate,the surface roughness will also become larger,the forming ability will decrease,and the alloy fluidity and formability will be at 1.25 at.% V.the best.The mechanical properties show that the hardness increases with the increase of V content,and the hardness is the highest(about 510 HV)at 6.25 at.%V.Under dry friction and wear conditions,the wear mechanism is mainly abrasive wear.With the increase of V content,the wear resistance gradually increases.At 6.25 at.%V,the wear resistance is the best.The compressive fracture mechanism is cleavage fracture.With the increase of V content,the compressive strength and plasticity both increase first and then decrease slightly.This is the combination of fine grain strengthening and intragranular segregation of microstructure.At 3.75 at.% V,the maximum compressive strength can reach 1048.95 MPa,and the elongation range varies from 9.12% to 11.43%,which indicates that V element has little effect on its plasticity.The corrosion resistance study shows that the corrosion resistance increases with the increase of V content in 1mol/L HCl solution,and the corrosion resistance of the alloy is best at 6.25 at.%V.