ZrCo-based hydrogen isotopes storage alloys: A review

ZrCo alloy has been considered as one of most promising materials for handling hydrogen isotopes in International Thermonuclear Experimental Reactor (ITER), due to its remarkable superiority in terms of de-/hydriding kinetics, thermodynamics, 3He trapping and security. However, hydrogen storage performances of ZrCo alloy demands further ameliorating to accommodate the complex working condition in storage and delivery system (SDS), involving comparable kinetics to depleted uranium (DU), low desorption temperature, stable 3He trapping ability and high reversible capacity. To solve these challenges, various modification strategies concerning multiple alloying, process regulation, surface decoration and bed optimization have been developed over the past decades. In this review, we present a comprehensive survey on the previous advances in improving these four aspects of hydrogen storage performances for ZrCo-based alloys. Firstly, basic hydrogen storage characteristics of ZrCo alloy are introduced. Then, the impacts of different modification strategies on de-/hydriding rates, desorption temperature, 3He trapping ability and cycling stability are respectively outlined based on theoretical calculation and experimental results. Meanwhile, alloying is declared as the most effective improvement avenue and the specific function of each element substitution is systematically provided. Specifically, lattice modulation for constructing stable isostructural de-/hydrogenation transformation shows the most effective impact on the improvement of cycling stability and anti-disproportionation property in ZrCo-based alloy by multiple alloying. Finally, the remaining challenges and further development of ZrCo-based hydrogen isotopes storage materials henceforth will be prospected.