Abstract: Zr2Fe alloy has been regarded as one of the most promising tritium getters in fusion reactors, owing to its ultra-low equilibrium hydrogen pressure and excellent hydrogen absorption kinetics. However, its practical application is greatly limited by the hydrogen induced disproportionation reaction, resulting in rapid degradation of hydrogen isotope storage capacity. In this work, first-principles calculations have been employed to systematically explore the site preference and diffusion behaviors of interstitial hydrogen atoms in Zr2Fe alloy. Four transition metals (Mn, Co, Ni, Cu) from the same period as Fe and with similar electronic structures are selected to substitute Fe in Zr2Fe. The doping effects on the hydrogen behaviors are explored in both Zr2Fe alloy and its hydride Zr2FeH5. The formation energies and electronic structures of interstitial hydrogen atoms as well as their diffusion pathways are carefully analyzed to elucidate the modification mechanisms at the atomic scale. This study provides theoretical insights for the modification and optimization of Zr2Fe-based alloys.

Key words: Zr₂Fe alloy, Transition metal doping, Hydrogen behaviors, First-principles calculations