Kinetic investigation of hydrogen diffusion and trapping in non-metallic inclusions/iron phase interfaces: A first-principles calculation

• Published in: International journal of hydrogen energy Vol. 166; p. 151022
• Main Authors: Ning, Yuanxing, Wang, Yan, Yang, Peixun, Li, Yuxing, Liu, Cuiwei, Wang, Cailin
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 09.09.2025
• Subjects: DFT calculation; Hydrogen embrittlement; Hydrogen segregation; Hydrogen trapping; Interface; Non-metallic inclusion; DFT calculation; Hydrogen trapping; Non-metallic inclusion; Hydrogen segregation; Hydrogen embrittlement; Interface
• ISSN: 0360-3199
• DOI: 10.1016/j.ijhydene.2025.151022

Non-metallic inclusions (NMIs) play an important role in the hydrogen diffusion and trapping process is well-recognized. In this study, the kinetic behavior of hydrogen diffusion and segregation at the NMIs/matrix interface was investigated by first-principles calculations, which is a novel aspect rarely explored in previous studies. NMIs in circumferential welds of X65 pipelines steel were selected as the study subjects. The TiN/Fe and MnO/Fe coherent interface was constructed based on the results of STEM-EDS and selected area electron diffraction analysis. The lattice mismatches of the heterojunction supercell interface were all less 5 %. The solution and segregation energies of hydrogen at different hydrogen trapping sites at the NMIs/matrix interface were investigated, and the corresponding segregation mechanisms were elucidated by analyzing the electron density difference and using hybridization orbital theory. Transition state search calculations for hydrogen escape from the trapping sites of TiN/Fe and MnO/Fe interface were carried out by applying climb image driven elastic band theory (Cl-NEB) based on the reactant structure and product structure. The solution energy and segregation energy of the TS trapping site at the TiN (001)/α-Fe (100) interface exhibit positive values, indicating a tendency to fail to trap hydrogen. The hydrogen segregation energies at the BS trapping site of the MnO (001)/α-Fe (100) interface are −8.624 eV and −8.741 eV respectively, owing to the formation of localized states at this interface. The prerequisite for hydrogen trapping at the interface is strong hybridization between the H atom and the atoms at the interface, accompanied by sufficient charge transfer. There is no positive correlation between the escape energy barrier and the segregation energy. Hydrogen segregation weakens the cohesive strength of the NMIs/matrix interface. These findings contribute to elucidating the mechanisms of hydrogen trapping at NMIs/Fe interfaces and deepen the understanding of hydrogen embrittlement mechanisms. •Significant differences in the capability of inclusions to trapped hydrogen.•Hydrogen trapping required strong hybridization with sufficient charge transfer.•Energy barrier for hydrogen escape relates to segregation energy and escape paths.•Hydrogen reduces cohesion of the non-metallic inclusions/matrix interface.