γ-TiAl based alloy is a kind of high temperature structural materials with wide application field. Improving its high temperature oxidation resis-tance is one of the research hotspots. The geometric properties, densities, average formation energies of atom, formation energies of interstitial oxygen (O) atom, aluminum (Al) vacancy and titanium (Ti) vacancy of 20 γ-TiAl based alloys with Mo content less than 9.26% (atomic percentage) were studied based on the first principles calculation. The results indicate that the density of each Mo substituted γ-TiAl based alloy system increases, but all of them are less than 4.5 g•cm-3, which still has the density advantage of replacing the traditional Ni based alloys. The total energy and the average atomic formation energy of each doped system are all negative, which show the system has good energy stability and can be predicted to be prepared by experiments. The stability of Mo doped system decreases gradually with the increase of dopant content. Through the calculation and analysis of the difference of formation energy of O atom (ΔEf(O)) and the difference (ΔEV) of formation energy of Al vacancy and Ti vacancy (ΔEV) in Mo doped γ-TiAl system, it is revealed that when the Mo content is 4.0%-7.4%, the alloy system doped with Mo can not only increase the height of barrier of O-atom diffusion, but also promote the improvement of Al vacancy diffusion ability and the inhibition of Ti vacancy diffusion ability. It plays an important role in the formation of continuous, compact and adherent oxide scale dominated by α-Al2O3 on the surface of γ-TiAl matrix, and provides a theoretical basis for the development of new materials with excellent oxidation resis-tance. © 2021, Materials Review Magazine. All right reserved.
