Effect of chromium addition on the reactivation of the titanium-iron-manganese (TiFe0.85Mn0.15) alloy

Abstract Titanium-iron (TiFe) is known to be highly sensitive to oxidation, and this impacts its use in hydrogen storage applications. To investigate the ability to control the surface oxidation of TiFe-based alloys, TiFe0.85Mn0.15 was used as a base alloy due to its ease of activation and the addition of Cr investigated to facilitate its re-activation upon oxidation. Upon the formation of TiFe0.85Mn0.15Crx (x = 0, 0.15 and 0.30) an improvement in reactivation was observed. After exposure of TiFe0.85Mn0.15Cr0.30 to air for 2 h, the alloy could be re-activated at 150 °C under a 3 MPa hydrogen pressure. In comparison, a temperature of 300 °C under the same hydrogen pressure was needed to re-activate TiFe0.85Mn0.15. This indicates that Cr addition provided to some extent resistance against deactivation. This is also reflected in the HP-DSC measurements where a partial oxide reduction was observed at 100 °C for the oxidized TiFe0.85Mn0.15Cr0.30 alloy as opposed to the 220 °C of TiFe0.85Mn0.15. The partially reduced species acted as catalytic sites for hydrogen activation.