H-sorption properties and structural evolution of Mg processed by severe plastic deformation

• We report good H-sorption properties of commercial Mg processed by SPD.
• The H-sorption properties are associated with adequate (0001) type texture.
• Small grain sizes are also relevant in the improvement of H-sorption properties.

MgH2-based nanocomposites are excellent candidates for hydrogen storage applications due to their high hydrogen gravimetric capacities, reversibility of the absorption/desorption reactions and low cost of Mg. A conventional route to obtain MgH2 is high-energy ball milling which involves processing in controlled atmosphere due to the poor resistance of the nanometric powder for air contamination (O2, H2O, etc.). In the present work we evaluated the H-sorption properties of bulk Mg samples produced by different severe plastic deformation (SPD) routes and we associated the results with their microstructural characteristics. The SPD techniques included high pressure torsion (HPT) and cold rolling (CR), applied to process commercial Mg and fine-grained Mg ribbons, which were obtained by rapid solidification. Enhanced H-sorption properties were observed for the sample processed by melt-spinning followed by cold-rolling and these properties were associated with refined microstructure and stronger (0 0 0 1) texture.