Nanocrystallization and hydriding properties of amorphous melt-spun Mg65Cu25Nd10 alloy

Amorphous Mg-based alloy Mg65Cu25Nd10 was prepared by melt spinning. Thermal stability and phase transition in the as-quenched alloy were studied by TEM, DSC, X-ray and electron diffraction. It was found that the crystallization process of melt-spun Mg65Cu25Nd10 ribbons consists of three steps. The first crystallization reaction at about 180 °C is connected with the formation of Mg2Cu nanocrystalline phase with average grain size in the range 5–10 nm, followed by formation of a coarser grained α-Mg crystalline phase (210–225 °C) corresponding to a second crystallization reaction. At higher temperatures a third exothermic effect (at about 320 °C) can be detected and the stable Mg2Cu, α-Mg and Cu5Nd phases are present with the biggest grain size about 100 nm. The hydrogenation characteristics of the as-quenched and the annealed samples (partially and fully crystallized) were compared as well. The amorphous Mg65Cu25Nd10 alloy shows the best initial hydrogenation rate and the maximum hydrogen capacity (3.2 wt.%) in comparison with those of partially crystalline and completely crystallized microstructural states.