A study on stability and bonding mechanism of bcc-Fe/Ni2AlTi interface based on the first-principles

• The bonding mechanism of bcc-Fe/Ni2AlTi interface was studied. • The F1T2 interface has the highest stability among the four interface models. • The stability of the bcc-Fe/Ni 2 AlTi interface is lower than that of the bcc-Fe/NiAl interface. Interfacial bonding plays a key role in composite performance. In this study, the interface properties of bcc-Fe/Ni 2 AlTi were explored using first-principles-based DFT simulations. The bcc-Fe(110)/Ni 2 AlTi(110) interface model was constructed based on the bcc-Fe(110) and Ni 2 AlTi(110) structures. Parameters including adhesion energy (W ad ), interface energy (γ int ), differential charge density, and density of states were determined to clarify interface stability at the atomic scale. The results showed that the F1T2 model exhibited the highest W ad (2.634 J/m 2 ), lowest γ int (1.962 J/m 2 ), and minimal atomic distortion, indicating that F1T2 is essentially the interface with highest thermodynamic stability. Specifically, the Ti-Fe charge interaction at the interface is significant, and a strong hybridization of the Fe-d orbital and the Ni-d orbital is detected. The synergistic effect of metal bonds and covalent bonds significantly strengthens interface bonding and enhances interface stability. However, the bonding strength and stability of bcc-Fe/Ni 2 AlTi were lower than those of bcc-Fe/NiAl. This is the key reason behind increased brittleness of ferritic alloys containing bcc-NiAl and Ni 2 AlTi phases. This study facilitates the understanding of interfacial bonding of bcc-Fe/Ni 2 AlTi, and provides references for next-generation of Fe-based alloys with extraordinary temperature resistance, high strength, and lightweight.