Microstructure And Properties Of Ti-Zr-Mo Alloy Fabricated By Laser Additive Manufacturing

The technology of laser additive manufacturing is an advanced manufacturing technology,which uses high-power laser beam as the heat source and directly produces any complex shape parts by layer-by-layer melting metal powder or wire stacking forming,it provides a new technical way for the manufacture of large and complex titanium alloy components.At present,it is being paid close attention all over the world,and is one of the leading directions in the advanced manufacturing field.Among them,the research and development of materials plays a vital role as basic research,but it is still relatively weak.The problem of special printing materials is still an urgent problem to be solved,and the types of special printing materials are still relatively scarce,the materials used are still based on the traditional alloy system,and the original development of the traditional alloy did not take into account the unique characteristics of the laser additive manufacturing,it is easy to produce metallurgical defects in the complicated physical metallurgical process of laser-added material manufacturing,which seriously affects the properties of the formed parts.Therefore,the development of a new alloy system suitable for laser additive manufacturing has become an important basis for the development of this advanced manufacturing technology.In this paper,on the basis of Ti-Zr straight melting point alloy with good formability and high melt stability,the β-Ti isomorphous stabilizing element Mo,which has a stabilizing effect on β-Ti,is used as the alloying element,taking the cluster plus connected atom model as the design criterion,the Ti-Zr-Mo alloy system was designed,and the alloy formed body was prepared by coaxial powder feeding on the pure titanium plate.X-ray diffractometer,scanning electron microscope and other material testing and analysis technology systems are used to systematically study the evolution relationship between the phase and microstructure of the alloy formed body and the Mo content.The Zygo surface profiler,hardness tester,friction and wear tester and other instruments are used to test and analyze the relationship between the mechanical properties,formability,corrosion resistance,friction and wear properties with different Mo contents.The research results of the designed Ti-Zr-Mo alloy system show that the five components of the system are all composed of single-phase β-ti solid solution under the condition of rapid dynamic non-equilibrium solidification made by laser additive,however,with the increase of Mo content,the lattice constant of β-ti solid solution decreases gradually due to the lattice distortion caused by Mo addition.The microstructure of the alloy is composed of columnar grain structure in the bottom interface bonding zone and equiaxed grains structure in other layers.With the increase of Mo content,the grain size is refined,and there is no obvious preferred growth orientation in the other layers outside the first layer at the bottom.At the same time,the Surface roughness of Ti-Zr-Mo alloy increases with the increase of Mo content,but the aspect ratio of single cladding layer decreases,the porosity of the alloy is also increased due to the influence of liquid-solid zone and convection intensity,but it still has good formability.In addition,with the increase of Mo content,the hardness and strength of the alloy and the friction and wear properties of the alloy under dry friction conditions are improved under the influence of fine grain strengthening and solid solution strengthening,but the plasticity of the alloy decreases slightly,and the corrosion resistance of the alloy is gradually improved in 1mol/L HCl solution.