First-principles thermodynamics and experimental study of interface oxidation in Ni/Ni₃Al structures

Area of Science:

• Materials Science
• Physical Chemistry
• Computational Materials Science

Background:

• Nickel-based superalloys possess vital anti-oxidation properties for industrial use.
• Prior research primarily examined single-phase NiAl or Ni3Al, neglecting multi-phase systems.

Purpose of the Study:

• To systematically investigate the atomistic oxidation behaviors of Ni/Ni3Al composites.
• To elucidate the oxidation mechanisms and identify stable surface configurations.

Main Methods:

• Employed first-principles density functional theory (DFT) and thermodynamic analysis.
• Conducted oxidation experiments on DD6 alloy to validate theoretical predictions.
• Analyzed surface formation energies and binding energies to understand oxidation pathways.

Main Results:

• Identified Ni(111) and Ni3Al(100)/(111) surfaces as the most stable configurations.
• Demonstrated that Ni3Al phase oxidizes preferentially, followed by Al-segregation and Ni phase oxidation.
• Showed oxygen adsorption enhances Al-segregation, leading to complete oxidation of Ni3Al(111) surfaces.

Conclusions:

• The selective oxidation of Al atoms forms a dense anti-oxidation membrane, enhancing material protection.
• Findings provide atomic-scale insights into the oxidation of two-phase composites.
• This research serves as a reference for future studies on oxidation and adsorption in multi-phase materials.