Hydriding characteristics of palladium and platinum alloyed FeTi

Fundamentals of Superior Properties in Bulk NanoSPD Materials

“…There have been many attempts to overcome this limitation. [112][113][114][115][116][117][118][119][120] Recent studies have shown that SPD processing is the way to achieve that, as such an activation process is no longer required when the TiFe is pre-processed by HPT ( Figure 15). [121] Furthermore, the HPT-processed sample is not deactivated even after storage in air for a prolonged period of time.…”

Synthesis of Nanostructured TiFe Hydrogen Storage Material by Mechanical Alloying via High‐Pressure Torsion

“…The presence of Ti and Fe may not be responsible for slow hydrogen transport into the bulk, because it is generally believed that the interphase boundaries in TiFe can act as hydrogen pathways for activation. [11][12][13][14][15][16][17][18][19] Although Fe is believed to act as a catalyst for surface activation of TiFe, the presence of Ti and Fe oxides on the surface may not make a positive effect for hydrogen dissociation. [10] Taken altogether, although the HPT process shows high capability to synthesize the nanograined TiFe intermetallics, such synthesis method is not able to reduce the activation temperature of synthesized material to room temperature.…”

“…[4][5][6] In 1974, the first successful results on hydrogen storage in TiFe at room temperature were reported by Reilly and Wiswall, but they found that the as-cast material should be activated by repeated exposure to vacuum and hydrogen atmosphere at temperatures as high as 673 K. [4] Later studies also showed that despite all advantages of TiFe, its difficult activation is a main drawback. [7][8][9][10] There have been several attempts to solve the activation problem of as-cast TiFe mainly using two strategies: 1) chemical activation by addition of a third element, such as Pd, [11] Ni, [12] Mn, [13][14][15][16] and Zr [17][18][19] and 2) mechanical activation by ball milling, [20][21][22] high-pressure torsion (HPT), [23][24][25] and cold rolling. [26,27] Although the exact mechanism for the activation of TiFe is still under argument, it is generally believed that the first strategy is based on the surface catalytic performance of elemental additives, and the second strategy is based on nanostructuring and introduction of hydrogen pathways into bulk, such as cracks, nanograin boundaries, and amorphous regions.…”

Tailoring the Kinetic Behavior of Hydride Forming Materials for Hydrogen Storage

“…In the case of room temperature hydrides, the presence of transition metals like Pd and Ni notably improves their activation behavior and kinetic properties. This fact was attributed to the active sites of these transition metals, located on the metal or alloy surface, which facilitated the hydrogen molecule dissociation and penetration across the oxides generated on the metal or alloy surface [67][68][69]. These hydrides are commonly prepared by arc melting since, as mentioned in Section 4.2, the milling process can cause hydrogen capacity losses.…”