Effects of Ni-substitution and F-treatment on the hydriding behaviors and microstructures of AB(2)-compound (Ti,Zr)(Mn,Cr)(2)

The effects of Ni-content and F-treatment of AB(2) compounds Ti0.5Zr0.5(Mn0.5Cr0.5)(2-x)Ni-x (x = 0.0 to about 1.4) on the initial activation characteristics, P-C-T property, and microstructure have been investigated. It was found that Ni can substitute into this AB(2) family of compounds which have the essentially single C14 Laves structure between x = 0.0 and about 1.0 Ni and become the C15 Laves structure between x = 1.0 and about 1.4 Ni. All the compositions were easily activated at 40 degrees C and 1.0 MPa H-2 pressure. This family of compounds exhibited high hydrogen storage capacity and low hysteresis. The plateau pressures could be raised over two orders of magnitude by the increase of Ni-content. The F-treatment, which has been successfully used on AB(5) compounds, such as LaNi4.7Al0.3 (1,2), did not show beneficial effects on this AB(2) family of compounds.