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

Abstract

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 V 92.5− x− y Zr 7.5Ti 7.5+ x− y M y (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.