Nanoscale Grain Refinement and H‐Sorption Properties of MgH₂ Processed by High‐Pressure Torsion and Other Mechanical Routes

Abstract

Abstract MgH 2 is a promising material for solid‐state hydrogen storage due to its high gravimetric and volumetric storage capacity and its relatively low cost. Severe plastic deformation (SPD) processing techniques are being explored as an alternative to high‐energy ball‐milling (HEBM) in order to obtain more air resistant materials and reduce processing times. In this work, Mg, MgH 2 , and MgH 2 –Fe mixtures were severely mechanically processed by different techniques such as high‐pressure torsion (HPT), extensive cold forging, and cold rolling. A very significant grain refinement was achieved when using MgH 2 instead of Mg as raw material. The mean crystallite sizes observed ranged from 10 to 30 nm, depending on the processing conditions. Enhanced H‐sorption properties were observed for the MgH 2 ‐based nanocomposites processed by HPT when compared with MgH 2 mixtures. Additionally, cold forging and cold rolling also proved effective in nanostructuring MgH 2 . These results suggest a high potential for innovative application with the use of low cost mechanical processing routes to produce Mg‐based nanomaterials with attractive hydrogen storage properties.