Corresponding author: fwang@swin.edu.au
Steel corrosion presents major economic, environmental, and safety challenges, particularly in chloride‑rich environments. At the atomic scale, corrosion reflects the competition between protective O adsorption and Cl‑driven depassivation. While these mechanisms are well established for ideal Fe surfaces, the role of surface defects remains inadequately resolved. In this ARC‑DP‑supported study, we employ spin‑polarised density functional theory (DFT) calculations to systematically evaluate how defects alter corrosion reactivity on Fe(100). Three surface models were examined: pristine Fe(100) (Fe(100)-P), adatom‑modified (Fe(100)-A), and vacancy‑defective (Fe(100)-V). Adsorption energies and electronic structures were calculated to quantify defect effects on O‑ and Cl‑adsorption at the most stable sites. The results show that O adsorption is strongest on the pristine surface, enabling robust passivation (Fe(100)-P > Fe(100)-A > Fe(100)-V). Vacancy defects substantially weaken O binding, suppressing oxide‑film formation, whereas adatoms have only a minor impact. In contrast, Cl adsorption is significantly enhanced at vacancy sites (Fe(100)-V > Fe(100)-P > Fe(100)-A), identifying vacancies as preferential Cl‑accumulation centres that accelerate passive‑film breakdown. These results establish vacancy defects as dual corrosion promoters that simultaneously hinder passivation and enhance Cl‑induced depassivation. Further mechanistic details and atomistic insights into these defect effects will be presented to illuminate how they inform defect‑engineered alloy design and advanced surface treatment strategies for improved corrosion resistance.
Key Words: Corrosion Mechanism, DFT, Defects, Passivation, Depassivation
#Abstract submitting to RACI National Congress https://www.racicongress.org.au/