Influence of Mn or Mn plus Fe on the hydrogen storage properties of the Ti-Cr-V alloy

To increase the hydrogen storage capacity and the plateau pressure of the Ti_0.32Cr_0.43V_0.25 alloy, a fraction of the Cr was replaced with Mn or a combination of Mn and Fe. When Mn was used alone, the effective hydrogen storage capacity increased to about 2.5 wt% though the plateau pressure showed no significant change. When Fe was added with Mn, however, both the effective hydrogen storage capacity and the plateau pressure increased. The BCC (body centered cubic) lattice parameter of the alloy decreased linearly with the Fe content, but it was not affected by Mn alone. The effective hydrogen storage capacity of the Ti_0.32Cr_0.32V_0.25Fe_0.03Mn_0.08 alloy was about 2.5 wt%, higher than 2.35 wt% in the original alloy. The estimated usable hydrogen stored in the Ti_0.32Cr_0.32V_0.25Fe_0.03Mn_0.08 alloy was 2.71 wt% in the temperature and pressure range of 293–353 K and 5–0.002 MPa, respectively.