The Construction Of Ti Metal Interaction Potentials

With the advancement of science and technology,metals and metal compounds have been widely used as high-temperature materials.Among them,Ti metal and Ti alloys are attracting much attention,as they can be a great heat-resistant material.In recent years,more and more people have studied the interatomic potentials of Ti metal and Ti alloys.Nowadays,a main approach of a more comprehensively study of materials performance is computer simulations,which at the atomic and molecular level.This simulation is based on the interaction potentials,it can proceed from the atomic level and solve some related material problems.At the same time,this simulation is also a new method to study the micro structure of the materials,so,for this computer simulation,it is very important to find a group of very precise interatomic potentials.The establishment of a group of high accuracy interatomic potentials is a complex task,it includes model selection,parameters and cut-off distance selection and determination,the test and the correction of interatomic potentials,and so on.Many factors can affect the accuracy of the interatomic potentials,such as the number of potential parameters,the location and size of the cut-off distances,and the fitting method.In this paper,the interatomic potentials of Ti metal is constructed in the framework of EAM,the parameters in the Ti metal interatomic potentials were fitted by the lattice constants?a?,the elastic constants(C_{1 1}?C_{1 2}?C_{1 3}?C_{3 3}?C_{4 4}?C₆₆),and the cohesive energies?E_c?.Finally,the interatomic potentials of Ti metal is constructed.In order to verify the accuracy of the interatomic potentials in this paper,using the interatomic potentials of the Ti metal,which has constructed in this paper to calculate the bulk modulus?B?,the average shear modulus?G?and the anisotropic ratio?A?,the results are ideal.In order to further test the accuracy of the interatomic potentials,in this paper,a further simple test of the accuracy of the Ti metal interatomic potentials is performed,that is,using the Ti metal interatomic potentials obtained in this paper to calculate the E-r relationship,and compared with the Rose curve,and the result of the curve contrast is ideal.At the same time,the structure stability of the three structures of Ti metal are calculated by the interatomic potentials that has constructed in this paper,the result is the Ti metal of fcc structure has the highest energy,followed by the Ti metal of the bcc structure,and the Ti metal of the hcp structure is the most stable at room temperature,consistent with the actual situation.As an application,using the interatomic potentials obtained in this paper to calculate the point defect property of the Ti metal,the mono-vacancy formation energy is in good agreement with the experimental values.Later,using the interatomic potentials obtained in this paper to calculate the di-vacancy formation energy of Ti metal,a total of six di-vacancy configurations are calculated,the six configurations correspond to the case where the distance between two vacancies is the first,second,third,fourth,fifth,and sixth neighbors distance,respectively,In the six di-vacancy configurations,the second configuration has the lowest formation energy,this configuration is the most stable and the easiest to form.Among the other configurations,the fourth configuration has the highest formation energy and is the most difficult to form,consistent with the results of the first-principle data,which are the first,second,and fourth configuration data.The calculation results of the di-vacancy binding energy of this six di-vacancy configurations show that only the results of the first and second configurations are positive,and the binding energy of the second configuration is the largest and most stable,and the binding energy of the other configurations is the same,all negative,indicating that the remaining configuration is difficult to exist,the di-vacancy binding energies of the fifth and sixth configurations,although negative,are very small,close to zero,indicating that there is little interaction between the vacancies of the two configurations,the di-vacancy formation energies of the fifth and sixth configuration are approximately equal to the sum of the two mono-vacancy formation energies.