Atomic-structure and charge redistribution modified by intrinsic strain in α-fe/TMN (TM=Ti/Zr/Hf/V/Nb/Ta) interfaces

Abstract

Metal/ceramics interfaces, ubiquitous in functional materials, alloys, and coatings/films systems, provide excellent mechanical and chemical properties, mainly originating from atomic structures and charge distribution at the hetero-interfaces. In the present work, the α-Fe/TMN (TM = Ti/Zr/Hf/V/Nb/Ta) interfaces were chosen as the typical metal/ceramic candidates to explore the atomic structures and electronic properties at such types of heterostructures. After full optimization, the relaxed models kept the stacking sequence OT (on top) of FeN, producing a slight difference in interfacial distance ( Δz ). Furthermore, a significant charge transfer emerged in interfacial Fe and N atoms, indicative of the stronger bond strength across the interfaces obtained from the analysis of planar-averaged charge density difference, PDOS, charge density and difference, partial charge density and ELF . Moreover, the increasing gain of interfacial N1 atoms and enhanced overlap of Fe and TM1 atoms could account for the higher adhesion strength of Fe/TMN. Finally, the amount of charge transfer for interfacial Fe1 was tiny compared to that of inner Fe4 atoms based on the Bader charge analysis, indicative of insignificant variation of interfacial ionicity. However, the magnetic moment (in μ B ) of interfacial Fe1 changed significantly compared to Fe4 atoms, indicating the charge redistribution, which enhanced the hybridization of N1- p and TM1- d states. One can conclude that the enhanced interfacial bonding strength could be ascribed to the strengthened hybridization of interfacial Fe1- d and N1- p covalence. These findings are relevant for a better comprehension of these specific configurations and improving technological modification of such kind of metal/ceramic system. • The relaxed interfacial models kept the stacking sequence of Fe–N (on top) OT. • The significant charge transfer results in the stronger bond strength across the interfaces. • The enhanced overlap of interfacial atoms account for the higher adhesion strength. • The magnetic moment of interfacial Fe1 changed significantly in comparison to that of Fe4 atoms.