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

The influence of V, Cr, Nb, Mo, Ta, and W alloying elements on the stability and adhesion properties of gamma-TiAl (111)/Al2O3(0001) and the alpha(2)-Ti3Al(0001)/Al2O3(0001) interfaces are studied via first principles calculations. All the considered alloying elements prefer to substitute for the Ti site in both the gamma-TiAl(111) and the alpha(2)-Ti3Al (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 gamma-TiAl/Al2O3 system. The alloying elements will enhance the bonding interactions of the alpha(2)-Ti3Al/Al2O3 interfaces and maintain the strength of the gamma-TiAl/Al2O3 interfaces, most of the alloyed interfaces own work of adhesion of lower than -2.5 J/m(2). Different charge transfer behaviors between Al2O3 scale and Ti-Al intermetallics is probably the major factor that enhancing the adhesion of the considered systems.