Hydriding Characteristics of FeTi-Based Ti-Fe-V-Mn Alloy*

Abstract

TiFe-based alloy / Hydrogen absorption / P-C-isotherms / Surface composition The hydrogen absorption characteristics of the FeTi-based alloy Tio.457Feo.447-V0.048Mn0.048 were studied by means of X-ray diffraction, EDS and AES. The alloys' resistance to contamination with oxygen and water vapor was determined. Addition of 5 at.% of manganese and vanadium does not change the absorption capacity but gives rise to a new phenomenon of dissociation plateau pressure values "smoothing" so that the isotherms exhibit no distinct region of monohydride existence. It was found that upon hydriding the surface composition changes greatly. The added alloying metals prevent the iron atoms from oxidation and play a catalytic rôle in the hydrogénation process.

Substitutional effects in TiFe for hydrogen storage: a comprehensive review

“…[195] The introduction of both V and Mn results in lower plateaus pressures, decreased hysteresis, flatter plateaus, good activation and capacity, showing a synergic effect of both Mn and V. [123] The effect of the double substitution in Fe-rich alloys (detailed composition reported in Table 4) was explored by Mitrokhin et al evidencing the formation of a secondary C14 Laves phase. [196,197] Combined…”

“…[196] Even if resistance to contaminants was not improved, easy activation was observed but with very slow kinetics. [196,197] [198] Substitution effect of Co over Mn has been explored by Qu et al [199]. An increase of the Co content decreases the cell volume of TiFe, while improving activation, resistance to pulverisation upon cycling and increasing capacity.…”

“…[194] The introduction of both V and Mn results in lower plateaus pressures, decreased hysteresis, flatter plateaus, good activation and capacity, showing a synergic effect of both Mn and V. [123] The effect of the double substitution in Fe-rich alloys (detailed composition reported in Table 4) was explored by Mitrokhin et al evidencing the formation of a secondary C14 Laves phase. [195,196] Combined Mn and V substitution reduces the pressure gap (V effect) between the two plateaus, that merge into one at lower pressure compared to pure TiFe, while enthalpy of reaction increases (Mn effect). [195] Even if resistance to contaminants was not improved, easy activation was observed but with very slow kinetics.…”

“…[195] Even if resistance to contaminants was not improved, easy activation was observed but with very slow kinetics. [195,196] TiFe0.80Mn0.20 with the addition of V was scaled up to 55 kg by Japan Metals & Chemicals Co. Lts and studied by Endo et al, showing easy activation under 10 bar and 80°C. [197] Substitution effect of Co over Mn has been explored by Qu et al [198].…”