A comparative study of the interfacial bonding properties and thermodynamic properties of bcc-Fe/MeAl (Me=Ni, Ti, Fe) interfaces based on first-principles methods

Abstract

Understanding the interfacial bonding and thermodynamic stability of Fe-based intermetallic is crucial for optimizing their mechanical properties and enhancing their high-temperature performance. This study employs first-principles calculations based on density functional theory (DFT) to investigate the interfacial bonding properties and thermodynamic stability of bcc-Fe/MeAl (Me = Ni, Ti, Fe) interfaces. Twelve distinct atomic stacking configurations were constructed for bcc-Fe(110)/NiAl(110), bcc-Fe(110)/TiAl(100), and bcc-Fe(110)/FeAl(110) interfaces. The interfacial adhesion work (W_ad) and interfacial energy (${\gamma }_{\mathrm{int}}$) were calculated to evaluate bonding strength and stability. Among all models, the T2N1 configuration of bcc-Fe(110)/NiAl(110) exhibited the highest adhesion work (3.992 J/m²) and the lowest interfacial energy (0.458 J/m²), indicating the most thermodynamically favorable structure. The electronic structure analysis revealed that the bonding at the bcc-Fe/MeAl interface is mainly composed of strong Fe–Ni and Fe–Fe interactions, with some weaker Fe–Al and Fe–Ti bonds, demonstrating both metallic and covalent characteristics. Phonon dispersion calculations confirmed the dynamic stability of the bcc-Fe(110)/NiAl(110) and bcc-Fe(110)/FeAl(110) interfaces, while bcc-Fe(110)/TiAl(100) exhibited imaginary frequencies, indicating instability. Furthermore, thermodynamic property calculations, including specific heat (C_v), entropy (S), internal energy (U), and vibrational free energy (F_vib), demonstrated that the bcc-Fe(110)/NiAl(110) system possesses superior thermodynamic properties compared to bcc-Fe(110)/FeAl(110). These findings provide theoretical guidance for the design and optimization of Fe-based intermetallic interfaces.