Capture and Diffusion of Hydrogen in Tantalum and Copper with Vacancy Defects: A First-Principles Study.

Area of Science:

• Materials Science
• Nuclear Engineering
• Computational Physics

Background:

• Oxygen-free copper faces hydrogen radiation corrosion challenges in nuclear applications.
• A novel tantalum-copper diffusion layer with high vacancy concentration was developed to improve corrosion resistance.

Purpose of the Study:

• To elucidate the mechanism behind the superior hydrogen trapping and diffusion resistance of the tantalum-copper diffusion layer.
• To investigate the interaction between hydrogen atoms and vacancies in tantalum and copper using first-principles calculations.

Main Methods:

• Density Functional Theory (DFT) calculations were employed to study hydrogen atom absorption by tantalum and copper vacancies.
• Formation energies and diffusion characteristics of vacancy-hydrogen complexes were analyzed and compared to interstitial configurations.

Main Results:

• Tantalum vacancies exhibit the lowest formation energy when capturing six hydrogen atoms, forming stable, spherical structures.
• Copper vacancies show higher formation energy than interstitial configurations when capturing up to six hydrogen atoms.
• Hydrogen capture significantly increases the migration energy of both tantalum and copper vacancies (>2.5 eV), enhancing hydrogen trapping capacity.

Conclusions:

• The high-vacancy tantalum-copper diffusion layer demonstrates superior hydrogen trapping capabilities.
• Vacancy-hydrogen complexes play a crucial role in stabilizing hydrogen and hindering its outward diffusion, improving material resistance to hydrogen radiation corrosion.