Fast reaction behaviors of AB-type Ti-Fe-Mn hydrogen storage alloys from lattice modification and in-situ formed yttrium hydride

• After adding Y, the TiFe phase lattice slightly expands, and a dispersed α-Y phase is formed. • The hydrogenation expansion of α-Y promotes hydrogen diffusion, shortening the incubation period from 4360 s to 180 s. • The hydrogen desorption kinetics of the alloy conforms to the G-B three-dimensional model. • Change from two-step dehydrogenation to one-step dehydrogenation after adding Y. Ti-based hydrogen storage alloy is considered a potential candidate for stationary hydrogen storage due to the ability to absorb and desorb H 2 at ambient temperatures. To achieve fast activation and high hydrogen storage capacity, the microstructural features and hydrogen storage behaviors of the AB-type Ti 1- x Y x Fe 0.8 Mn 0.2 alloys are investigated. With the addition of Y, only a small part of Y is dissolved into the TiFe phase, and most of Y forms a dispersed α-Y phase in the alloy. The incubation period for the first hydrogenation of the alloy at 100 °C decreased from 4360 s to 180 s. This is mainly attributed to the alloy fragmentation caused by the hydrogenation expansion of α-Y phase. The hydrogenation capacity of the Ti 0.95 Y 0.05 Fe 0.8 Mn 0.2 alloy is 1.79 wt% at 30 °C, which is only 0.06 wt% lower than the TiFe 0.8 Mn 0.2 alloy. The dehydrogenation behavior of the alloy conforms to the G-B model, which indicates that the diffusion of hydrogen atoms is the main limiting factor. The dispersed YH x phase accelerates the diffusion of hydrogen atoms, resulting in a decrease in the dehydrogenation enthalpy change value, and the dehydrogenation of the alloy hydride changes from two steps to one step.