Structure and electrochemical hydrogen storage behaviors of RE-Mg-Ni-Co-Al-based AB2-type alloys prepared by melt spinning

Abstract

The AB2-type La0.8-xCe0.2YxMgNi3.4Co0.4Al0.1 (x = 0–0.2) alloys were successfully fabricated by melt spinning. The changes of the thickness, the structure and electrochemical hydrogen storage behaviors caused by different spinning rate were investigated. The alloys have a base phase LaMgNi4 phase and an impurity phase LaNi5 phase. Melt spinning has impacts both on the macro characteristics and microstructures. The results show that increasing spinning rate results in a reduction of the average thickness of the ribbons, an increase of lattice constants and a decrease of the grains size. Moreover, it incurs the content of the LaMgNi4 phase increase and that of the LaNi5 phase decrease. The alloys achieve to the highest discharge capacities at the initial electrochemical cycle. The discharge capacity visibly declines, whereas the life-span considerably grows with increasing spinning rate. Furthermore, the electrochemical kinetics increase to a maximum value and decrease again with spinning rate growing.