Development And Application Of Interatomic Potentials For Ti₂AlNb Alloys

Material,one of the three pillars of the modern national economy,related to the foundation of all walks of life,is a research field which can not be separated from the development of modern industry and science and technology.At present,new materials have become the most cutting-edge research direction of materials.The development of economic industry requires materials to meet higher levels of performance.Metal materials,as mature traditional materials,also put forward higher requirements for their performance and processing technology,which often appear in major national scientific research projects and large projects.The aerospace field has gathered a lot of light high strength structural materials,high temperature resistant materials,high performance coating materials and new composite materials.As a pearl on the industrial crown,aero engine is a collection of excellent materials.Ti₂AlNb-based alloy,as a rising star in lightweight high-temperature resistant materials,shoulders the mission of a new generation of high-performance structural materials and have great development potential.The alloy has good plasticity at room temperature and high structural strength,which is suitable for the field of materials requiring bearing,compressive and light density.It has excellent fatigue resistance at high temperature compared with other alloy materials,and is not easy to break or crack under long stress.Ti₂AlNb alloy unlike pure metal whose structure is simple and properties is single.the alloy is due to the combination of multiple elements,it has the potential to develop rich propertials.to develop and improve the propertials of the alloy,it is necessary to study the interaction between atoms from the composition of the alloy and to explain the microscopic mechanism behind the propertials of the material from the atomic level,so as to guide the preparation and application of the material in reality more scientifically and systematically.The first-principle calculation based on density functional theory and the simulation calculation based on interatomic potentials have become very mainstream means to study the properties of materials.Compared with the traditional experiment and methods of using advanced instrument measurement,using these methods with low cost,whose calculation speed is fast,has not time and geographical limitation.In this paper,the various properties of alloy materials are calculated by these two methods.However,for the former,there are many commercial software available on the market.For the latter,the specific calculation and simulation process is important,and more importantly,the interatomic potential itself is the most important factor that determines the effect of calculation and simulation.In terms of the atomic configuration of Ti₂AlNb-based alloy itself,it is difficult to obtain uniform single crystal configuration in the macroscopic scale in the actual preparation process,but there may be a certain amount of orderly arrangement in each region of the crystal.Ashish Pathak et al.described the three ordered configurations of Ti₂AlNb alloy by the first principle method.In this paper,the interatomic potential of Ti₂AlNb alloy was developed based on the three ordered configurations.The development of the interatomic potential is extremely complex,and the researchers of material simulation need to find a more appropriate interatomic potential.The interatomic potential of pure metals and binary alloys in the academic community exists in large quantities and the development work is very mature,while the interatomic potential of multi-alloys is relatively small.For the interatomic potential developed in this paper,the embedded interatomic potential suitable for metals and alloys is selected.By trying various fitting strategies,this paper chooses to only fit the pair potential between different types of atoms,that is,to develop the interatomic potential of alloys on the basis of three developed pure metal potential functions.In order to provide a database for potential function fitting,this paper first uses the first principle method to calculate the various properties of three ordered phases,and then uses these databases to fit the parameters of the potential function model.Finally,the molecular dynamics simulations of B2 phase,D0₁₉ phase and O phase are carried out.In this paper,the first principle is used to prepare for the development of potential function and provide a rich database,such as the calculation of the lattice constant,cohesive energy,elastic modulus,stacking fault energy and the formation energy of multiple defects of the alloy.In view of the various defects of B2 phase,this potential function was tested by simulation calculation,and the results of the interatomic potential of Ti-Al-Nb developed by Farkas et al.were compared.It was found that the interatomic potential developed in this paper can well reproduce the defects,elastic modulus and other properties of Ti₂AlNb-B2 alloy,and the effect is also good in testing the cohesive energy of the three ordered phases.On the one hand,the work in this paper provides a way to develop the interatomic potential of multicomponent alloys,and on the other hand,it provides a choice for the workers who simulate and calculate the Ti₂AlNb alloys.