Energetic segregation of B, C, N, O at the γ-TiAl/α2-Ti3Al interface via DFT approach

The effects of small atom impurities (B, C, N, O) segregation at the gamma-TiAl/alpha(2)-Ti3Al interface were studied employing density functional theory (DFT) method. Energetic and bonding properties of the most stable interstitial configuration in the TiAl(111)/Ti3Al(0001) interface with and without segregated solutes were investigated. Results found that the octahedral interstices are energetically the preferential location for interstitial impurities at the TiAl/Ti3Al interface. Based on the data of interfacial energy, alloying with B and C atoms can destabilize the gamma/alpha(2) interface, while N and O atoms are beneficial for the stability by reducing the interface energy compared to the pure gamma/alpha(2) one. The most expected reductions are found for O impurity that makes the best stability. Besides, the calculation results of cleavage energy indicate that the segregation of B, N, and O will strengthen the gamma/alpha(2) interface, while the presence of C can maximally improve the ductility. Furthermore, charge density difference was computed to analyze interfacial atomic bonding behaviors. The mechanical properties are expected to be greatly improved in TiAl alloys reinforced wear-resistance coating and other functional devices after adding micro-alloying elements.

Automated summary

The study found that alloying with B and C atoms can destabilize the TiAl/Ti3Al interface, while N and O atoms are beneficial for stability. Among them, adding O impurity has the best effect on stability. Additionally, B, N, and O segregation will strengthen the gamma/alpha(2) interface, while C can greatly improve ductility.