Microstructural characterization and hydrogenation performance of Zr_xV_5Fe(x=3-9) alloys

Zr_xV₅Fe(x = 3, 5, 7, 8, 9) alloys were designed to investigate the influence of Zr addition on hydrogenation performance. The alloys were prepared by arc melting and then annealed at 1273K for 168 h. The results showed that the alloys were composed of α-Zr and C15–ZrV₂ phases. The cell volume of C15–ZrV₂ phase firstly increased and then decreased as the content of Zr increased, while the reversed trend was found for the cell volume of α-Zr phase, which was related to the stoichiometric ratio of elements. α-Zr phase distributed in C15–ZrV₂ phase matrix in Zr_xV₅Fe(x = 5, 7, 8, 9) alloys, among which Zr₇V₅Fe alloy showed the best distribution. The PCT curves of the alloys under 623 K, 673 K and 723 K showed that the hydrogen absorption plateau pressure of the phases in different alloys decreased gradually with the increasing content of Zr. However C15–ZrV₂ phase in Zr₇V₅Fe alloy had the lowest hydrogen absorption plateau pressure at room temperature, which was consistent with the change tendency of the corresponding cell volume. Moreover, the kinetic curves of hydrogen absorption at 623 K revealed that Zr₇V₅Fe alloy with the smallest average particle size and the largest phase boundary area showed the fastest hydrogen absorption kinetics. Compared with other four alloys(including St707 alloy), Zr₇V₅Fe alloy is more suitable for the use of getter.