Effect of high zirconium content on hydrogenation properties and anti-poisoning ability of air-exposed TiFe alloy

Abstract

In order to improve the anti-poisoning ability of air-exposed TiFe alloy, the TiFe+x wt.% Zr (x=8, 12 and 16) alloys were synthesized by arc melting and subsequently exposed in air for different time. The results show that all samples handled in air can absorb the hydrogen directly without any incubation time. In addition, their first hydrogenation kinetics increases with the proportion of zirconium. And for the samples exposed in air for 35h, all samples also can absorb the hydrogen without any heating and mechanical treatment, but x=8 sample needs a long incubation time. Further study, it can be found that each alloy exposed in air for 35h includes three phases: a TiFe main phase with very small amount of zirconium, a hcp secondary phase with high proportion of zirconium and very small titanium phase. Also, more hcp secondary phases are beneficial for the improvement of the first hydrogenation kinetics but also lead to higher loss of capacity after first absorption and desorption. Above results suggest that introducing high zirconium content can improve the anti-poisoning ability of TiFe alloy effectively. This may be because that the bright phase (hcp phase) probably can⿿t be oxidized as easily as the dark phase (TiFe phase).