On the structural, hydrogenation behaviour and computer simulation studies of P-C-T of Zr1−2xMmxTixFe1.4Cr0.6 (x = 0.03, 0.05, 0.07, 0.09) alloys

In this paper an investigation has been made on the effects of vacuum annealing treatment at 1000 °C for 100 h on the hydrogen storage capacity of Mm, Ti and Cr substituted Zr1−2xMmxTixFe1.4Cr0.6 (x = 0.03, 0.05, 0.07, 0.09) Laves phase alloys. XRD patterns show that annealing has no significant effect on the structure of the alloy. However, the crystal lattice strain and defects decreased and grain size increased for all compositions studied after annealing. These materials exhibit high uptake of hydrogen as compared to those by the as-synthesized alloy. The optimum alloy corresponds to the composition Zr0.9Mm0.05Ti0.05Fe1.4Cr0.6. It shows a storage capacity of ∼1.94 wt.% and kinetics of ∼5.83 × 10−4 m3/s/kg. This is one of the highest storage capacity reported for any ZrFe2 type alloy. The unit cell volumes have been found to correlate with storage capacity. The P-C isotherms at various temperatures have been simulated by a suitable mathematical model. For this, the randomized variables ΔH and ΔS have been evaluated experimentally. These have been used as input parameters for simulation. The simulated and experimental curves have been found to match closely.