Hydrogen storage performances, kinetics and microstructure of Ti1.02Cr1.0Fe0.7-xMn0.3Alx alloy by Al substituting for Fe

For achieving good economic and environmental benefit, capacity of hydrogen storage alloys plays an important role in high-pressure-metal-hydride system of refueling station. Hydrogen storage characteristics of Ti1.02Cr1.0Fe0.7-xMn0.3Alx (0 <= x <= 0.1) alloys with main C14 structure were analyzed by Pressure-Composition-Temperature, XRD, HRTEM, SEM, EDS, ICP and XPS measurements, which were prepared by plasma arc melting and subsequent heat treatment. When Al content is lower than 0.05, it can improve the hydrogen reversible storage capacity from 1.58 to 1.65 wt% at 233 K. The pulverization resistances are enhanced by addition of Al (Al content: 0.05, 0.1), and the ductile fractures appear on the particle surfaces. Based on kinetic analysis, the dehydrogenation rates are fast with low activation energies between 7.4 and 9.9 ki/mol. The mechanism for Al effecting the capacity is that, the big size effect dominates the capacity increase as Al content less than 0.05. Otherwise, higher Al2O3 content covering on the particles surface deteriorate hydrogen storage capacity as Al content exceeding 0.05. Among them, Ti1.02Cr1.0Fe0.68Mn0.3Al0.02 alloy has the best comprehensive properties for high-pressure metal hydride system in hydrogen refueling station. How to utilize the alloy to assemble the compressor and measure the toxicity resistance to impurity gas in H-2 may be the future work. (C) 2020 Elsevier Ltd. All rights reserved.