First-principles investigation on shear deformation of a TiAl/Ti3Al interface and effects of oxygen

We have calculated the generalized stacking fault energies including the unstable stacking fault energy (γus) and the cleavage energy (γcl) at the clean and the oxygen-doped TiAl/Ti3Al interface using a first-principles method in order to investigate the mechanical properties of the interface. The [ 01 1 ¯ ] ( 111 ) slip system exhibits the lowest γus and the largest γcl/γus among the selected four typical slip systems, showing that the shear deformation in this slip system is energetically favored. Oxygen at the TiAl/Ti3Al interface increases the stacking fault energies, and reduces γcl/γus for all the selected slip systems, suggesting the presence of oxygen reduce the ductility of the binary phase TiAl-Ti3Al alloy.