MgH2-based nanocomposites prepared by short-time high energy ball milling followed by cold rolling: A new processing route

• A new processing route to produce MgH2-based nanocomposites is presented.
• Low desorption temperature, very fast desorption kinetic behavior are reported.
• Very fine additive particle size distribution and the better level of mixing are reported.

A new processing route consisting of a short-time high energy ball milling (HEBM) step followed by cold rolling (CR) to produce MgH2-based nanocomposites was investigated. Samples of pure MgH2 and MgH2-mixtures containing 2 mol% of FeF3 were processed under air atmosphere and their effects on the microstructure and the hydrogen storage properties were studied in detail. X-ray Diffraction (XRD) analysis on all samples revealed crystallite sizes in the nanometer range for the beta-MgH2 and FeF3 phases (beta (beta): ∼8–13 nm and FeF3: ∼16–21 nm). No extra crystallite size reduction was observed for the HEBM + CR samples in comparison with those only cold rolled. Scanning electron microscopy (SEM) evaluation together with elemental composition analysis indicated a finer size distribution of additive particles and also a more intimate level of mixing for the HEBM + CR mixture than for the mixture obtained only by CR. These features were associated with the HEBM step applied before the CR. These characteristics led to a lower hydrogen desorption temperatures and enhanced desorption kinetics behavior for the HEBM + CR samples in comparison with the CR samples.