Influence of preparation methods on the hydrogen absorption properties of Zr7V5Fe getter alloy

Abstract

Zr-V-Fe alloys are promising getter materials due to their remarkable hydrogen storage properties. In this work, the effects of preparation methods including annealing, melt-spinning, and melt-spinning & annealing on the microstructure as well as the activation properties and hydrogen absorption properties of Zr7V5Fe alloy are systematically investigated. Phase structure investigations show that annealed alloys have the largest cell volume of the main hydrogen-absorbing phase ZrV2. Compared to annealed alloys, the cell volume of α-Zr phase and ZrV2 phase is smaller in melt-spun alloys. As for the melt-spun & annealed alloy, the cell volume of ZrV2 phase decreases and the cell volume of α-Zr phase increases after annealing. And the PCT curves show that with the cell volume of the ZrV2 phase increasing, the plateau pressure decreases while the hydrogenation capacity increase accordingly. As a result, the annealed alloy has the lowest plateau pressure about 0.02 Pa and the highest hydrogenation capacity about 1.4 wt% at 623 K. The kinetic curves illustrate that the hydrogen absorption process is diffusion-controlled for all of the alloys. The melt-spun & annealed alloy has the best hydrogen absorption kinetic performance because it has a well homogeneous distribution of α-Zr phase after melt-spinning and annealing treatment. Melt-spun as well as melt-spun & annealed alloys have no incubation period and exhibit superior activation properties compared to annealed alloys. This is due to the higher content of Zr elements and thinner passivation layer on the surface of melt-spun and melt-spun & annealed alloys than that of annealed alloy.