Effect of additives on the hydrogen sorption properties of mechanically alloyed composites based on Mg and [formula omitted]Ni

Abstract

The effect of additives on the hydrogen absorption–desorption properties of three series of composites (i) 85% Mg–15% Mg 2 Ni 1 - x Me x (Me=Fe, Co; x = 0 , 0.1, 0.3); (ii) 75% Mg–15% Mg 2 Ni –10% V and 75% Mg–15% Mg 2 Ni –10% C and (iii) 90% Mg 2 Ni –10% V and 90% Mg 2 Ni –10% C obtained by mechanical alloying in different atmospheres was studied. The Mg 2 Ni 1 - x Me x , vanadium and graphite additives were found to have a positive effect on the hydriding kinetics of magnesium, especially favorable due to the presence of cobalt in the composites 85% Mg–15% Mg 2 Ni 1 - x Co x which preserved a high-absorption capacity with decreasing temperature (4 wt% H 2 at a hydriding temperature of 423 K). With 90% Mg 2 Ni –10% V (C) composites, the additive showed an analogous positive effect on the hydriding kinetics and absorption capacity as compared with that of pure Mg 2 Ni . The role of the milling atmosphere (argon or hydrogen), with respect to the absorption–desorption characteristics of these composites was also studied.