B2 NiAl Coatings Alloyed with Rare Earth Element Y: A First-Principles Study

NiAl coatings are critical for protecting components in high-temperature environments. In order to improve the mechanical properties of NiAl coatings, in this study, the elastic and electronic properties of NiAl coatings alloyed with different contents of rare earth element (REE) Y were investigated by using the density functional theory (DFT). It was found that NiAl alloys with 3.125 at.% of Y exhibited higher hardness, while those with 6.25 at.% of Y showed better ductility. This phenomenon is explained by population analysis, which reveals that the covalency of Ni-Ni and Al-Al bonds is stronger in Ni15YAl16 than in Ni7YA8, whereas Ni-Al bonds exhibit stronger covalency in Ni7YAl8. Additionally, the ionicity of Y-Al bonds is higher in Ni7YAl8 than in Ni15YAl16. These results deepen our understanding of how rare earth elements modify the mechanical properties of NiAl alloys, thereby providing a theoretical basis for further exploration of their strengthening mechanisms.