Hydrogen storage behavior and microstructural feature of a TiFe-ZrCr2 alloy

Abstract

The microstructural feature as well as the hydrogen storage properties of as-cast and annealed TiFe-6 wt % ZrCr2 alloy samples has been investigated. Three phases, TiFe with the BCC structure, TiFe2 with the C14 Laves hexagonal structure and Ti2Fe with a cubic structure, are observed in both alloy samples, although the amount of TiFe2 as a second phase is significantly reduced with a fragmented shape in the annealed sample. Both samples are hydrogenated under 31 bar of hydrogen at room temperature without a harsh activation process, although the annealed sample is hydrogenated after an incubation period of approximately 40 h. The pressure-composition-temperature curves of both samples are not much different from each other, exhibiting a maximum capacity of 1.7 wt% H-2. No significant degradation of hydrogen capacity is observed during 50 cycles of hydrogen sorption for the as-cast sample. The second phase TiFe2 regions seem to assist the first hydrogenation of the alloy by acting as gateways for supplying hydrogen to the inside of the alloy. (c) 2020 Elsevier B.V. All rights reserved.