Work

Optimizing grain refinement, mechanical properties, and oxidation resistance of Ni3Al intermetallic through Fe doping

Year: 2025

Type: article

Abstract: • Fe doping refines the grain size and increases twin boundary content in Ni 3 Al. • DFT simulations reveal that Fe doping lowers the stacking fault energy of Ni 3 Al. • Fe doping decreases the hardness of Ni 3 Al. • Fe doping inhibits oxide spallation during oxidation of Ni 3 Al in air. • A four-layer oxide structure forms during the oxidation of Ni 3 Al. The Ni 3 Al bond-coat in thermal barrier coatings has attracted significant attention due to its phase equilibrium effect with the γ/γ’ Ni-base substrate, which effectively mitigates interdiffusion between the coating and substrate. However, its oxidation resistance and mechanical properties still require improvement. In this study, Fe was doped into Ni 3 Al at varying concentrations (0.1–1 wt%), and its effects were systematically investigated using both in-situ and ex-situ characterization techniques, complemented by density functional theory calculations. The results indicate that Fe doping effectively suppresses oxide scale spallation and enhances the oxidation resistance of Ni 3 Al, with the optimal performance observed at 0.5 wt% Fe. The oxidation mechanism of Ni 3 Al is further elucidated. Additionally, Fe doping refines the grains, increases the density of twin boundaries and stacking faults, and reduces the hardness of Ni 3 Al. First-principles calculations confirm that Fe doping lowers the stacking fault energy of Ni 3 Al by modulating atomic bond energies. In conclusion, the grain size, mechanical properties, and oxidation resistance of Ni 3 Al can be optimized by Fe doping.

Source: Materials & Design

DOI: 10.1016/j.matdes.2025.113968