| TiAl-based alloys have important applications in the aerospace field due to their excellent comprehensive properties.For the development of this new type of material,improving the high temperature oxidation resistance of TiAl-based alloys is of great significance.Through MS software,this paper doped Mo and Y elements into Ti27Al27 supercells and got a series of systems SMij and SYij（1≤i+j≤5）.First-principles calculation based on density function theory and theoretical method,are used to study and analyze the structures and properties of these systems,especially their oxidation resistance.The results show that the average atomic formation energies of each Mo and Y substitution dopedγ-TiAl-based alloy systems are negative.It indicates that systems possess energy stability and can be prepared experimentally.Except system SY23 and SY32,other systems have mechanical stability.Although the density of substitution dopedγ-TiAl system increase to some extent,it is still far less than that of NiAl alloy.This gives them a certain of advantages in aviation field.Based on the calculation and comprehensive analysis of interstitial O atom,Ti and Al vacancy formation energies,we can predict that five Mo substitution doped configurations(SM11,SM21,SM30,SM31 and SM50)and five Y substitution doped configurations(SY30,SY31,SY40 SY41 and SY50)have the potential to improve oxidation resistance properties of materials.They can not only increase the barriers that hinder the diffusion of O atoms,but also enhance the diffusion capacity of Al vacancy and inhibit the diffusion of Ti vacancy.It is conducive to the formation of dense oxide films on the surface ofγ-TiAl matrix,and it is favorable to the improvement of the oxidation resistance of the materials.System SM31 has more advantages than SY30 in blocking interstitial oxygen diffusion,while system SY30 has obvious advantages in inhibiting Ti diffusion and promoting Al diffusion.They are both theγ-TiAl based alloys which are worth exploring. |
