Enhancing adhesion of Al2O3 scale on Ti-Al intermetallics by alloying: A first principles study.

• Negative formation energies of alloyed Ti-Al/Al 2 O 3 systems were observed. • The alloying elements will enhance the adhesion of α 2 -Ti 3 Al/Al 2 O 3 interfaces. • There are connections between the stability, adhesion and the electronic structures. The influence of V, Cr, Nb, Mo, Ta, and W alloying elements on the stability and adhesion properties of γ-TiAl(111)/Al 2 O 3 (0001) and the α 2 -Ti 3 Al(0001)/Al 2 O 3 (0001) interfaces are studied via first principles calculations. All the considered alloying elements prefer to substitute for the Ti site in both the γ-TiAl(111) and the α 2 -Ti 3 Al(0001) surfaces, with occupation energy differences of more than 0.2 eV and 1.0 eV lower than Al site, respectively. The interfaces studied here own negative formation energy except the Cr alloyed γ-TiAl/Al 2 O 3 system. The alloying elements will enhance the bonding interactions of the α 2 -Ti 3 Al/Al 2 O 3 interfaces and maintain the strength of the γ-TiAl/Al 2 O 3 interfaces, most of the alloyed interfaces own work of adhesion of lower than −2.5 J/m2. Different charge transfer behaviors between Al 2 O 3 scale and Ti-Al intermetallics is probably the major factor that enhancing the adhesion of the considered systems. [ABSTRACT FROM AUTHOR]