Hydriding and structural characteristics of thermally cycled and cold-worked V–0.5at.%C alloy

Low and high-pressure hydriding of V–0.5at.%C

“…We present a combination of earlier results, corroborated with recent experiments, on the effect of carbon as an alloying element on the hydriding properties of vanadium [49,50]. According to the V-H phase diagram, it is possible to observe the vanadium-hydrogen solid solution (a phase) at temperatures above 473 K [31]; isotherms are measured at higher temperatures (>473 K) for V-0.5at.%C hydrides.…”

“…Dislocation motion during hydriding may contribute to this affect since there was a large volume change during cycling between the b 2 M c phases. Further details on these cycling experiments may be found elsewhere [49,50]. A comparison of isotherms obtained from this study with V-0.5%C, the pure vanadium data of Fagerstroem et al, and the data of Griffiths et al show that the isotherms are virtually the same.…”

“…First, we reported low-pressure gas phase charging to obtain a M b 1 isotherms for V-0.5at.%C at several temperatures, and then high-pressure isotherms (b 2 M c) at 298 K. X-ray and scanning electron microscopic characterization of the materials were also shown. Some data has been presented in this paper on thermal cycling between the b 2 M c phases, although more details may be found in Sharma et al [49,50].…”

Synthesis of nanocomposite hydrides for solid-state hydrogen storage by controlled mechanical milling techniques

“…Therefore, the lowering of DSC desorption temperature is most likely due to the presence of VH 0.81 rather than V. The average grain size of the ␤-MgH 2 and VH 0.81 constituent after 20 h of ball milling is within 14-16 nm and 14-23 nm, respectively. The hydride VH 0.81 exists within the range from VH 0.45 to VH ∼0.9 [12] and is usually designated as ␤ 2 phase having a body centered tetragonal (BCT) crystallographic structure [12,13]. The PCT (pressure-composition-temperature) plateau for a mixture of ␤ 2 + ␥(VH 2 ) is between 3 and 4 atm at 40 • C [12] and the mixture is considered to be stable at room temperature as opposed to ␥(VH 2 ) which is unstable at room temperature but shows slow kinetics of desorption [12].…”

Cyclic hydrogenation stability of γ-hydrides for Ti25V35Cr40 alloys doped with carbon

“…After 1000 cycles, the degradation of effective hydrogen capacity was reduced from 20% for VH x to 5% for V 0.995 C 0.005 H x . In addition, a significant reduction in both the plastic deformation of g-VH 2 and premature fracture of vessels can be obtained by adding a small amount (0.5 at%) of interstitial carbon into the vanadium [17,18]. Kim et al also suggested that using an interstitial nitrogen element could slow down the hydrogenation degradation of annealed Ti 33 V 37 Mn 30 alloys [19].…”