Novel insights into heterogeneous nucleation interface properties between La2O3 and γ-TiAl: First-principles calculations

The refinement effect of the rare earth oxide LaO on γ-TiAl by first-principles method was investigated in this study. The mismatch between different low-index interfaces of LaO and γ-TiAl was calculated, and the interface with the smallest mismatch was selected to construct the LaO/γ-TiAl interface. The stability and electronic structure of the interface were assessed, and the efficacy of LaO as a heterogeneous nucleation core for γ-TiAl was analyzed. The results reveal that the LaO (100)/γ-TiAl(100) interface displays the smallest mismatch, which is 4.36 %. Four LaO (100)/γ-TiAl(100) interface models were constructed based on various surface terminations and stacking sequences. Among these models, the O-Al model exhibits the highest interfacial binding energy of 5.062 J/m, while the O-Ti model demonstrates the lowest interfacial energy of −3.300 J/m. The primary bond type in the interface models is ionic bonding. Therefore, from the geometric and energetic aspects of the interface structure, it can be inferred that LaO can act as a heterogeneous nucleation core for refining the γ-TiAl phase, with a preference for forming O-Ti type heterogeneous nucleation interfaces.