Construction And Application Of Nb,Al Interatomic Potentials And Study On Interatomic Potential Of NbAl₃ Alloy

With the continuous progress of science and technology in society,the quality of people's life also improves,the requirements of materials'related properties also become more and more strict,the widely application of Nb alloy,which is a good thermal protection materials in the aerospace industry because of its good resistance to high temperature characteristics,in addition,Nb alloy is also a good choice for productive materials are used in craft and industry.Through constantly exploration,it is found that Nb-Al system alloy has the advantages of good mechanical properties and strong resistance to high temperature,which is widely used in the industrial field.Among them,NbAl₃ alloy can also be used to manufacture ceramic crafts.In order to better understand the relative properties of Nb,Al and NbAl₃ alloy,its mechanism can be explored in the microscopic field from the atomic point of view.In numerous methods of exploration,Molecular dynamics simulation method has a good application,makes the material on the atomic scale simulation,so as to determine the material properties accurately,it is necessary to add defect performance to atomic simulation,so that we can know that failure mechanism in the process of material in use,however,the interatomic potential is the most important of the process.There are varies of the methods to construct the interatomic potentials,and the first step to construct the traditional interatomic potential is to select the potential model,then the determination of the potential function.The construction of interatomic potentials are considered from two aspects in this paper,one is the form of potential function should be simple possibly rather than too complex,try to reduce the number of potential function parameters properly,so that the efficiency of the molecular dynamics simulation will be improved,the other is when fitting the potential parameters using the method of reproducing material related properties to complete,which is also necessary for almost all the development of traditional interatomic potential at present.In this paper,the interatomic potentials of the two metal elements of Nb,Al are constructed on the basis of EAM potential and trying to build the interatomic potential of NbAl₃ alloy.Using the method of the least squares to fit the two kinds of elemental electron density function and minimum mean square error method to define the potential function parameters,On the one hand,experimental datas such as lattice constant,binding energy and vacancy formation energy are used in the fitting data;on the other hand,calculation data based on the first principle are also used as a supplement.The work of testing and verifying the interatomic potentials in this article constructed By Molecular dynamics simulation to accomplish,using LAMMPS software to simulate the related performance of materials,first of all,verify the state equation of elemental,results in accordance with the basic Rose universal equation,secondly,the stability of two kinds of elemental structures is verified,the results are in conformity with the experiment.Defects play an important role in mechanical properties.Therefore,the defect energy of two kinds of elemental materials is also simulated,and the results show that the interatomic potential constructed in this paper can better describe the defects properties.