Effect of Cu on dehydrogenation and thermal stability of amorphous Mg-Ce-Ni-Cu alloys

The alloying element component is very crucial in improving the hydrogen storage performance of amorphous alloys. In this work, quaternary amorphous Mg70−xCe10Ni20Cux (x = 3, 7.5, 10) alloys were prepared by melt-spinning and the effect of Cu on hydrogenation and dehydrogenation were investigated in comparison with the Mg70−xCe10Ni20 amorphous alloys. The initial hydrogenation kinetics of amorphous Mg70−xCe10Ni20Cux (x = 0, 3, 7.5, 10) was improved with the increase of Cu content according to the kinetics measured at a temperature below crystallization temperature. As hydrogen is absorbed, an amorphous-amorphous transition occurred, and relatively high Cu content would lead to phase separation in the hydrogenation process. Amorphous phase have much higher crystallization temperature after it absorbs hydrogen and the addition of Cu could increase the crystallization activation energy of amorphous hydrides. In addition, the increase of Cu content could reduce the dehydrogenation temperature of amorphous hydrides, which gives a significant indication for future improving research of the hydrogen desorption performance of Mg based amorphous hydrides.