Thermal, Microstructural and Electrochemical Hydriding Performance of a Mg65Ni20Cu5Y10 Metallic Glass Catalyzed by CNT and Processed by High-Pressure Torsion

Abstract

A Mg65Ni20Cu5Y10 metallic glass was produced by melt spinning and was mixed with a 5 wt.% multiwall carbon nanotube additive in a high-energy ball mill. Subsequently, the composite mixture was exposed to high-pressure torsion deformation with different torsion numbers. Complimentary XRD and DSC experiments confirmed the exceptional structural and thermal stability of the amorphous phase against severe plastic deformation. Combined high-resolution transmission electron microscopy observations and fast Fourier transform analysis revealed deformation-induced Mg2Ni nanocrystals, together with the structural and morphological stability of the nanotubes. The electrochemical hydrogen discharge capacity of the severely deformed pure metallic glass was substantially lower than that of samples with the nanotube additive for several cycles. It was also established that the most deformed sample containing nanotubes exhibited a drastic breakdown in the electrochemical capacity after eight cycles.

The Effect of Severe Plastic Deformation on the Hydrogen Storage Properties of Metal Hydrides

“…At the same time, the formation enthalpy of the hydrogenation increases remark-ably which is the most pronounced at the perimeter region of the HPT-disk 70). When CNTs are added to the melt-spun Mg 65 Ni 20 Cu 5 Y 10 amorphous alloy before HPT straining, the electrochemical hydrogen absorption capacity increases substantially, confirming that nanotubes play a crucial role in the absorption of hydrogen of Mg-based glasses subjected to severe plastic deformation 71).…”