Vanadium-based BCC alloys: phase-structural characteristics and hydrogen sorption properties

This work was focused on the studies of vanadium-based “low-temperature” bcc alloys as H storage materials. Both as cast and annealed at 1100 ° C quaternary alloys V92.5−x−yZr7.5Ti7.5+x−yMy (M = Cr, Mn, Fe, Co, Ni; x = 0 , 10; y = 0 , 7.5) were studied. They were characterised by XRD, PCT hydrogen absorption–desorption measurements ( T = 30 –120 ° C) and thermal desorption spectroscopy studies of H desorption from the saturated hydrides ( T = − 100 to 800 ° C). The thermodynamics of the VH∼2↔ VH∼1 transition and hydrogen sorption capacities ( 1.55 , … , 1.80 H/M) were found to be significantly influenced by the substituting M-element. The reversible hydrogen storage capacity ( T 100 ° C, P > 0.1 bar) reaches 50–60% of its overall value. Complete hydrogen desorption proceeds in vacuum at T 300 ° C. The major future challenge of the work is in increasing of the easy-reversible part of the H storage capacity corresponding to transformation VH∼2↔ VH∼1 by reducing the content of H in the monohydride.