Hydrogen Trapping in bcc Iron

Area of Science:

• Materials Science
• Computational Materials Science
• Solid State Physics

Background:

• Hydrogen embrittlement in steel is a critical failure mechanism.
• Atomic-level understanding of hydrogen (H) interactions with defects is crucial for theoretical descriptions.

Purpose of the Study:

• Investigate the interaction between atomic H and defects in ferromagnetic body-centered cubic (bcc) iron.
• Determine H trapping profiles and concentrations at various defects as a function of temperature.

Main Methods:

• Density functional theory (DFT) calculations were employed.
• Calculated H trapping profiles in the bulk lattice, vacancies, dislocations, and grain boundaries (GBs).

Main Results:

• Identified a hierarchy of H trapping energies at common crystal lattice defects.
• Determined the most attractive H-trapping sites in bcc iron.
• Calculated H concentrations at defects, enabling investigation of H-enhanced decohesion at GBs.

Conclusions:

• DFT calculations provide fundamental insights into H localization in iron.
• The findings contribute to understanding hydrogen embrittlement mechanisms at the atomic level.
• Identified specific defect sites that strongly attract hydrogen, crucial for material design.