About this Abstract |
| Meeting |
2026 TMS Annual Meeting & Exhibition
|
| Symposium
|
Vacancy Engineering in Metals and Alloys
|
| Presentation Title |
Hydrogen's Influence on Vacancy Diffusion in Metals: Inhibitor or Catalyst? |
| Author(s) |
Shihao Zhang, Shihao Zhu, Junping Du, Singenobu Ogata |
| On-Site Speaker (Planned) |
Shihao Zhang |
| Abstract Scope |
Vacancy-mediated diffusion dominates mass transport in metals at elevated temperatures, yet its alteration by dissolved hydrogen remains poorly quantified because vacancies and hydrogen interact in complex, temperature-dependent ways. We present a unified thermodynamic-kinetic framework that incorporates hydrogen-Gibbs excess into vacancy-jump statistics, enabling quantitative predictions of hydrogen's effect on vacancy mobility over wide temperature and hydrogen-chemical-potential ranges. Applications to five model systems - bcc-Fe, fcc-Cu, fcc-Pd, fcc-Ni, and hcp-Zr - reveal two distinct regimes. At lower temperatures or lower hydrogen chemical potentials, hydrogen strongly binds to vacancies, elevates the migration barrier, and slows diffusion. At higher temperatures or higher hydrogen chemical potentials, transient hydrogen-vacancy complexes lower the saddle-point energy, enhancing vacancy transport. The resulting diffusivity maps clarify when hydrogen acts as a drag or a catalyst for vacancy motion. These insights advance our fundamental understanding of hydrogen‑affected phenomena such as creep, precipitation kinetics, and embrittlement in structural alloys. |
| Proceedings Inclusion? |
Planned: |
| Keywords |
Modeling and Simulation, Computational Materials Science & Engineering, |