H₂ Absorbing-desorbing characterization of the TiVFe alloy system

Twenty six kinds of alloys with compositions Ti(33-47 mol%)-V(42-67 mol%)-Fe(0-14 mol%) were tested to find the most suitable composition for hydrogen absorbtion (including tritium recovery and storage). The best alloy composition was found to be Ti_43.5V_49.0Fe_7.5, and this alloy was able to absorb hydrogen up to 3.90 wt% ( H M = 1.90) at 253 K. The hydrogen capacity was estimated to be 2.4 wt% when hydrogen was absorbed at 253 K and desorbed at 573 K at 1 atm hydrogen pressure. The hydrogen absorption rate at 253 K was faster than that of the LaNi₅H₂ system at 293 K. Conspicuous changes in pressure-composition (p-c) isotherms were not found after 50 cycles of hydrogen absorption and desorption. All dehydrided alloys are bcc, dihydrides of the alloy are fcc. Among the series of TiVX alloys (X = Fe, Co, Ni, Cr and Pd), iron was found to be the best substituent element for X. Two kinds of industrial ferrovanadium alloys containing about 4 wt% of impurities (Al, Si, etc.) were tested to prepare the alloys. Remarkable differences in the p-c isotherms were observed which may be due to the effect of impurities in the ferrovanadium.