High-Pressure Torsion of Pure Magnesiutm: Evolution of Mechanical Properties, Microstructures and Hydrogen Storage Capacity with Equivalent Strain

摘要

The hardness-strain behavior of pure Al after processing by high-pressure torsion (HPT) is different from other pure metals because of its low melting temperature (T_m) and high stacking fault energy (SFE) [1,2]. In most metals, a steady-state level is reached directly following an initial increase with straining [1], However, in pure Al, the hardness initially increases with increasing strain and, after reaching a maximum, decreases to a constant level [2]. The hardness-strain behavior like Al may be observed in pure Mg because both Al and Mg are similar in terms of T_m and SFE [3],It is well known that Mg is a good candidate for a hydrogen storage material. [4]. Main drawbacks of Mg for this application are that absorption and desorption temperatures are considerably high and hydrogenation reaction is too slow. It is an important issue if the absorption speed can be increased at low temperatures after HPT processing.