Improving hydrogen permeability and sustainability of Nb_(30)Ti_(35)Co_(35) eutectic alloy membrane by substituting Co using Fe

摘要

The microstructure and hydrogen permeation performance of Nb(30)Ti(30)Co(35-x)Pe(x) (x = 0, 5, 10, 15, 20) alloys have been investigated. With Fe less than 15 at%, the as-cast Nb(30)Ti(35)Co(35-x)Pe(x) ingots exhibit fully eutectic structure. When the Fe content is higher than 15 at%, primary bcc-(Nb, Ti) phase appears in combination with eutectic structure. Substituting Co using Fe leads to slightly increased hydrogen solubility but highly enhanced hydrogen permeability, which comes mainly from the increased hydrogen concentration-independent diffusion coefficient D*. With Fe content up to 10 at%, Nb30Ti35Co35-xFex membranes exhibit stable and higher hydrogen permeation flux than Nb30Ti30Co35 at 673 K during hydrogen permeation test up to 72 h. Nb(30)Ti(30)Co(35-x)Pe(x) alloys of fully eutectic structures exhibit no hydrogen-induced failure when cooled down to room temperature under hydrogen atmosphere, indicating the potential application of the membrane at lower temperature range. An optimal combination of hydrogen permeability and hydrogen embrittlement resistance is achieved at 10 at% Fe, since further increase of Fe leads to comparable D* as that of Nb30Ti35Co25Fe10 but higher hydrogen solubility. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.