Achieving Anti-Disproportionation Performance Enhancement and Distorted Inverse-Disproportionation Reaction...

Area of Science:

• Materials Science
• Nuclear Engineering
• Computational Chemistry

Background:

• Zirconium-iron (Zr2Fe) alloys are investigated as tritium-getter materials for the International Thermonuclear Experimental Reactor (ITER).
• Existing Zr2Fe alloys suffer from inverse disproportionation and poor anti-disproportionation, limiting their practical use.
• Improving the stability and reversibility of hydrogen storage in these alloys is critical for fusion energy applications.

Purpose of the Study:

• To computationally screen and experimentally validate the effects of substituting iron with cobalt, copper, and nickel in Zr2Fe alloys.
• To enhance the hydrogen storage properties and anti-disproportionation behavior of Zr2Fe-based materials.
• To optimize Zr2Fe alloys for tritium-getter applications in the International Thermonuclear Experimental Reactor (ITER).

Main Methods:

• Theoretical computational screening was employed to predict the impact of substitutions.
• Experimental synthesis and characterization of Zr2Fe1-xMx alloys (M = Co, Cu, Ni; x = 0.1-0.5).
• Hydrogen storage capacity testing, X-ray diffraction (XRD), transmission electron microscopy (TEM), and density functional theory (DFT) analyses.

Main Results:

• Partial substitution of Fe with Co, Cu, and Ni successfully corrected inverse disproportionation and achieved full reversibility in hydrogen storage.
• Zr2Fe0.8Cu0.2 and Zr2Fe0.7Ni0.3 alloys demonstrated excellent hydrogen storage properties.
• Significant increases in the kinetic energy barriers for hydriding disproportionation were observed (e.g., from 87.88 kJ/mol for Zr2Fe to 184.35 kJ/mol for Zr2Fe0.8Cu0.2).
• TEM confirmed a deceleration of hydriding disproportionation kinetics.
• DFT analysis revealed that improved anti-disproportionation results from homogenized and stabilized Zr-H bonds and suppressed disproportionation-favoring chemical environments.

Conclusions:

• Partial substitution of Fe with Co, Cu, or Ni effectively enhances the anti-disproportionation properties and hydrogen storage reversibility of Zr2Fe alloys.
• Optimized alloys like Zr2Fe0.8Cu0.2 and Zr2Fe0.7Ni0.3 show great promise as tritium-getter materials for ITER.
• The study provides a mechanistic understanding of how these substitutions improve alloy stability for fusion applications.