| With the development of science and technology,the progress of society and the improvement of people's quality of life,the materials used in various fields are diverse,and the requirements for the use of materials properties are also constanly increasing.The development of titanium alloy has always been a focus issue.During the exploration process,it was found that TiAl alloy has the advantages of high strength,good corrosion resistance and light weight.More suitable for aerospace research,it has become an important material for use in aerospace engines and aircraft.Due to the long-term service of the engine in a high-intensity working environment,the performance requirements of the material are extremely demanding,which becomes another major problem.Undoubtedly,understanding the failure mechanisms in the process of material commissioning,the introduction of atomic simulations related to tissue and defects has become an urgent issue.The premise of carrying out atomic-scale simulation work is to use accurate and reliable interatomic potentials.However,the performance results of material defects obtained by the current calculation of the interatomic potential are not ideal,so the development of accurate and reliable interatomic potential has become the key to solving the problem.This paper develops the interatomic potential from two perspectives.First,the form of the interatomic potential function is as simple as possible,and the potential parameters are as little as possible to facilitate large-scale molecular dynamics simulation.The second is to ensure that the interatomic potential has good performance in defect performance,especially stacking fault energy,in order to use molecular dynamics to study the behavior related to plastic deformation of materials.In this paper,the interatomic potentials of Ti,Al and TiAl alloys are developed under the EAM framework,Proposed a new form of potential function.The fitting parameters are determined by the method of minimization mean square deviation.The relevant data involved in the fitting are from the experimental values and the first The principle calculates the value.Firstly,the E-r relationship of Ti,Al and TiAl alloys was investigated,which is in good agreement with the Rose binding energy curve.Secondly,the structural stability of Ti and Al metals was investigated,which is consistent with the existing results.Defect performance affects the mechanical properties of materials.This paper uses LAMMPS software to study the defect-related properties of Ti,Al and TiAl alloys.The defect formation properties such as vacancy formation energy,self-interstitial formation energy,surface energy and stacking fault energy of Ti and Al metals,as well as vacancy formation energy and anti-position formation energy of TiAl alloy were calculated.The obtained results are in good agreement with the first principle calculated values and experimental values.Because the interatomic potentials that do not consider the angle in the past are not satisfactory in terms of stacking fault energy,the calculation results are relatively low.In this paper,we try to improve the description of the interatomic potential in the stacking fault energy.The calculation result of the metal Ti layer fault energy developed in this paper has reached 71mJ/m~2,and the stacking fault energy of metal Al has reached 105mJ/m~2,the value of the stacking fault energy calculated by using the same method EAM potential has been improved.At the same time,in the process of constructing the potential function,it is found that if the accuracy of the layer fault energy is satisfied,the accuracy of other defect properties(such as self-interstitial formation energy)will be reduced.To this end,in this paper,as far as possible to ensure the accuracy of the self-interstitial formation energy and other defects,the stacking fault energy can be improved as much as possible to better simulate the deformation behavior of the material. |
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