Low temperature de/hydrogenation in the partially crystallized Mg60Ce10Ni20Cu10 metallic glasses induced by milling with process control agents

Abstract

Slow hydrogen de/absorption kinetics and high hydrogen desorption temperature are still great challenges for both crystalline and amorphous Mg-based alloys. In this work, through using ethanol (E) and ethylene glycol (EG) as milling process control agents (PCAs), partial and controllable crystallization of the melt-spun Mg60Ce10Ni20Cu10 metallic glass was achieved. The microstructure of the as-milled powders and corresponding hydrides was characterized by DSC, SEM, TEM and XRD. De/hydrogenation properties were measured by automatic Sieverts-type apparatus and TG-MS. It was found that the PCAs could lead to partial crystallization of the Mg60Ce10Ni20Cu10 metallic glass due to the dissolving of oxygen into the amorphous structure from PCAs. The introduction of a small amount of the nanocrystals promoted greatly hydrogen de/absorption properties of the melt-spun Mg60Ce10Ni20Cu10 alloy. The hydrogenation temperature could be decreased to below 100 °C and the initial hydrogen desorption temperature of the EG-added hydride could be decreased to below 150 °C. The structure evolution of the de/hydrogenated samples of the EG-added powder was also studied. The hydrogen-induced crystallization was evidently observed in the hydrogenated sample. The ethanol and ethylene glycol was found to be effective milling PCAs to create a composite structure of amorphous and crystalline, and the composite structure greatly enhanced the de/hydrogenation properties. However, the structural stability and reversibility of such composite structure during hydrogenation were still great challenges.