Influence of Impurities on Adhesion at the TiAl/Al2O3 Interface

The influence of substitutional impurities on adhesion at the TiAl/Al₂O₃ interface with an oxygen termination has been studied by the projector augmented-wave method within the density functional theory. It has been shown that transition metals and a number of s,p-elements substituting for the interfacial titanium atom reduce adhesion, whereas Group VB and VIB elements enhance chemical bonding at the interface. The local densities of states, charge density distribution, overlap populations for interfacial atom bonding, and other electronic characteristics have been calculated that make it possible to reveal key factors influencing adhesion at the alloy–oxide interface. A correlation has been found between the influence of impurities on bonding energy at the inner and outer interfaces. A comparison of obtained data with those for the interface with Ti-enriched Ti₃Al alloy shows that the interface loses strength with decreasing Ti content in the alloy.