Improved hydrogen storage properties of TiFe alloy by doping (Zr+2V) additive and using mechanical deformation

In this paper, the effects of doping, cold rolling and forging on the microstructure and hydrogen storage properties of air exposed TiFe + x wt.% (Zr+2V) (x = 0, 4, 5 and 6) alloys were studied. The results showed that all doped samples had similar crystal structure: bcc TiFe main phase and hcp secondary phase. Doping (Zr+2V) can improve obviously the first hydrogenation kinetics of TiFe alloy due to the presence of hcp secondary phase. Further study, we found that the process of cold rolling and forging could reduce the crystallite size of x = 4 sample but forged sample showed a smaller crystallite size. Then it also should be noted that x = 4 forged sample showed the fastest hydrogenation kinetics, highest hydrogen capacity and good cycling stability. By analyzing the kinetic model, all handled x = 4 samples agreed with GB3D model, which meant 3D growth, diffusion controlled with decreasing interface velocity.