Isostructural Transition of Zr0.7Hf0.15Nb0.15Co0.6Cu0.15Ni0.25 Alloy for Isotope Trapping Minimization and High-Temperature Durability Enhancement

The launch of International Thermonuclear Experimental Reactor project paves the way to wide adoption of DT fusion energy as future energy source. Efficient fuel cycle to minimize strategic tritium inventory proves crucial for commercially viable fusion technologies. ZrCo alloy is considered as a promising candidate for fast isotope handling. However, cycling degradation caused by hydrogen-induced disproportionation results in severe tritium trapping, thus impeding its practical application. Herein, an isostructural transition is successfully constructed with low hysterisis, ameliorated plateau flatness of pressure-composition isotherms and improved high-temperature durability for hydrogen trapping minimization. Specifically, the optimal Zr_0.7Hf_0.15Nb_0.15Co_0.6Cu_0.15Ni_0.25 alloy adopts Hf-Nb and Cu-Ni as Zr and Co side doping elements, exhibiting substantial thermodynamic destabilization with nearly 90 °C reduction of delivery temperature, and significant kinetic promotion with a threefold lower energy barrier. More importantly, both hydrogen utilization and cycling retention of optimal alloy are increased by about twenty times compared with pristine alloy after 100 cycles at 500 °C. Minimized disproportionation driving force from both isostructural transition and suppressed 8e hydrogen occupation realizes full potential of optimal alloy. This work demonstrates the effectiveness of combining isostructural transformation and high-temperature durability improvement to enhance the hydrogen utilization of ZrCo-based alloys and other hydrogen storage materials.