Crystal structure and hydrogen storage properties of body centered cubic 52Ti–12V–36Cr alloy doped with Zr7Ni10

• Two synthesis methods were performed to dope 52Ti–12V–36Cr alloy with Zr7Ni10.
• Upon hydrogenation, the as-cast body centered cubic phase transforms into face centered cubic phase.
• Easiness of the first activation and close results for thermodynamic parameters for both doping methods.

The crystal structure and hydrogen sorption properties of 52Ti–12V–36Cr doped with Zr7Ni10 have been investigated. Two doping methods were used: (i) melting all the components together (single melt) and (ii) melting the alloy and Zr7Ni10 separately and thereafter re-melting them together (co-melt). The XRD patterns of both single melt and co-melt samples showed that these alloys crystallize in a body centered cubic (BCC) crystal structure. Upon hydrogenation, both doped 52Ti–12V–36Cr BCC alloys turns into Face Centered Cubic (FCC) phase.The single melt alloy exhibits a zirconium and nickel rich phase at the grain boundaries. This phase is well-distributed into the matrix and makes a connected network. The same network microstructure was observed in the co-melt. The single melt alloy exhibits an incubation time before its first hydrogenation (activation) whereas the co-melt alloy immediately started to absorb hydrogen. For both samples, the subsequent hydrogenation kinetic is fast. The maximum hydrogen capacities of the single melt and co-melt alloy are respectively 3.4 and 3.2 wt.%, but the high stability of these hydrides prevents them to desorb at room temperature. Single melt and co-melt alloys have similar thermodynamic parameters.