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<p>In situ observation of Fe-Cr-Ni alloys at 1100&#xa0;°C under Ar using Laser confocal microscopy (LSCM), combined with electron probe microanalyzer (EPMA) and X-ray diffractometer (XPS) analysis, presents preferential selective oxidation of Cr to form Cr<sub>2</sub>O<sub>3</sub>. Oxide nucleation initiates at grain boundaries and evolves into spot-like and island-like structures with extended oxidation time. Thermodynamics and elemental diffusion kinetics analysis suggest that the sequence of Gibbs free energy for oxide formation is Cr<sub>2</sub>O<sub>3</sub>, Fe<sub>3</sub>O<sub>4</sub>, Fe<sub>2</sub>O<sub>3</sub>, and NiO. Moreover, the faster diffusion rates at grain boundaries compared to the bulk matrix drive preferential Cr oxidation and accumulation at these sites. First-principles calculations comparing Cr-doped <i>γ</i>-Fe (111) with undoped <i>γ</i>-Fe (111) show reduced adsorption energy and density of states for the doped surface, with the B-H site identified as the optimal Cr adsorption location. Cr doping also enhances O<sub>2</sub> molecule dissociation efficiency, and hybridization of Cr p-orbitals with O d-orbitals provides evidence for Cr increased tendency toward selective oxidation.</p>

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Insights into the Selective Oxidation of Cr in Fe-Cr-Ni Alloys Under Extra Low Oxygen Partial Pressure: Experimental and First-Principles Study

  • 期刊论文

  • 发表日期：

    2026年3月18日

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  • Guangming Cao,
  • Hengxiang Yu,
  • Qinglong Li,
  • Haohong Wu,
  • Hongbing Wang,
  • Yujia Liu,
  • Ning Liu,
  • Silin Li

摘要

In situ observation of Fe-Cr-Ni alloys at 1100 °C under Ar using Laser confocal microscopy (LSCM), combined with electron probe microanalyzer (EPMA) and X-ray diffractometer (XPS) analysis, presents preferential selective oxidation of Cr to form Cr2O3. Oxide nucleation initiates at grain boundaries and evolves into spot-like and island-like structures with extended oxidation time. Thermodynamics and elemental diffusion kinetics analysis suggest that the sequence of Gibbs free energy for oxide formation is Cr2O3, Fe3O4, Fe2O3, and NiO. Moreover, the faster diffusion rates at grain boundaries compared to the bulk matrix drive preferential Cr oxidation and accumulation at these sites. First-principles calculations comparing Cr-doped γ-Fe (111) with undoped γ-Fe (111) show reduced adsorption energy and density of states for the doped surface, with the B-H site identified as the optimal Cr adsorption location. Cr doping also enhances O2 molecule dissociation efficiency, and hybridization of Cr p-orbitals with O d-orbitals provides evidence for Cr increased tendency toward selective oxidation.