Hydrogen storage thermodynamics and dynamics of Mg-Y-Ni-Cu based alloys synthesized by melt spinning

Excessive heat stability, poor kinetics of hydrogen absorption and desorption reaction are viewed as the major setbacks for the Mg-based hydrogen storing materials application. The microstructures of samples Mg25 < b >-xYxNi9Cu (x = 0, 1, 3, 5, 7) alloys were observed by XRD, SEM, and TEM. Besides, aiming at studying the characteristics of hydrogenation/dehydrogenation, the Sievert instrument, DSC and TGA were applied in the experiments. Substituting Mg with Y can promote the formation of the second phase YNi3 but does not transform the Mg2Ni major phase. This substitution greatly prompts the amorphization. The increase of Y dosage triggers a mild decrease in the absolute values of Delta H and Delta S and remarkably boosts the improvement of dehydrogenation kinetics. Moreover, the increase in Y amount brings on a decrease in hydrogen absorption capability. The hydrogen desorption activation energy markedly lowers with increasing Y content (the E-a(de) values of as-spun Y-0 and Y-3 samples are 71.38 and 66.13 kJ/mol, severally, and E-k(de) values of them are 69.03 and 65.53 kJ/mol, respectively), which brings about the promotion of dehydrogenation kinetics of the experimental samples.