Effects of thickness and Ti substitutions on the anti-disproportionation behavior of ZrCo alloy films

Abstract

ZrCo alloy has been considered as a tritium storage material to replace uranium for large-scale hydrogen isotope storage and delivery in tritium plant of the magnetic confinement nuclear fusion reactor. However, the disproportionation of ZrCo greatly obstructed its aspects to engineering application. A multifaceted understanding about the intrinsic nature of disproportionation reaction, and proposing anti-disproportionation strategies from material design have always been the bottleneck and hotspot in the tritium science and technology field. Herein, we studied the anti-disproportionation properties of Zr(Ti)Co alloy with thin film structure, and the effects of film thickness and Ti substitutions on the anti-disproportionation properties of the films were obtained. Firstly, a series of ZrCo films with different deposited time were prepared by magnetron sputtering instrument. The disproportionation ratio of the 2 h deposited ZrCo film (1.641μm) is 23.9%, and attenuated with the increase of film thickness. It indicates that the anti-disproportionation properties of the film structure is significantly better than that of ZrCo particle (68%). The microtopography analysis shows that the micro stress in the film structure is beneficial to hinder the disproportionation process. However, the hydrogenation reaction is also obviously inhibited in the ZrCo film. In addition, Ti doping can further improve its anti-disproportionation performance (10.3–7.3% for the 2 h deposited Zr1-xTixCo film) without significantly reducing the hydrogen absorption capacities of the ZrCo flims. The anti-disproportionation performance is closely related to the weakened interaction between Zr and H atoms, after Ti doping into the ZrCo flim, leading to the impaired driving force for disproportionation reaction. The study in this work can provide an important reference for the anti-disproportionation modification of ZrCo alloys.