Abstract:

In order to develop rare earth magnesium based hydrogen storage alloys with high cycle life and high hydrogen storage performance for new energy vehicles,the microstructure,phase composition and hydrogen storage properties of the cast and annealed ingot/rapidly quenched（La_0.7Mg_0.3）Ni_x（x=2.0,2.5,3.0） hydrogen storage alloys were investigated.The results showed that when x=2.5,the hydrogen storage alloy prepared by rapid quenching had good hydrogen absorption and desorption plateau pressure,and the complete dehydrogenation characteristic was shown in the PCT curve,and the hydrogen absorption capacity was about 1.44%（mass fraction）.After annealing at 850~950 ℃,the hydrogen absorption and desorption plateau of（La_0.7Mg_0.3）Ni_2.5 hydrogen storage alloy prepared by ingot method was higher and wider than that of（La_0.7Mg_0.3）Ni_2.0 hydrogen storage alloy,which indicated that the former had relatively better hydrogen absorption and desorption performance;the hydrogen absorption and desorption plateau pressure of（La_0.7Mg_0.3）Ni_2.5 hydrogen storage alloy at different annealing temperatures was close.The hydrogen and dehydrogenation capacity could reach 1.6%（mass fraction）.The LaNi₅ and（LaMg）Ni₃ phases in （La_0.7Mg_0.3）Ni_x hydrogen storage alloys by ingot casting and rapid quenching would gradually transform into（LaMg）₂Ni₇ phase with the increase of annealing temperature.The surface powder particles of （La_0.7Mg_0.3）Ni_2.5 hydrogen storage alloys prepared by ingot casting and rapid quenching were minimum at 950 ℃ and 900 ℃,respectively.

Key words: components, La-Mg-Ni alloy, phase, hydrogen storage property, micromorphology