Mechanical milling of Mg, Ni and Y powder mixture and investigating the effects of produced nanostructured MgNi4Y on hydrogen desorption properties of MgH2

• Milling was not suitable method for synthesizing of MgNi4Y from elemental powder.
• After heat treatment of 25 h milled powder at 600 °C, MgNi4Y appeared in the powder.
• The release of H2 at 350 °C was maximum in 30 h milled MgH2 + 10 wt% MgNi4Y powder

It has been reported that intermetallic compounds could be used to improve hydrogen storage properties of Mg-based alloys. In this study, an attempt was made to synthesize the MgNi4Y compound from pure Ni, Mg and Y elemental powders via the combination of mechanical milling and heat treatment methods. In this regard, powders were ball milled in different conditions and then heat treated at 400 and 600 °C for 4 h to investigate the effect of temperature on the formation of MgNi4Y intermetallic compound. The characteristics of mixtures were evaluated via (XRD) and (SEM) methods. It was found from the results of XRD analysis that ternary intermetallic compound was not formed completely via ball milling alone. Nanostructured intermetallic compound was formed after heat treatment of milled powder at 600 °C for 25 h. Furthermore, addition of 5 and 10 wt% of the produced intermetallic compound to MgH2 decreased hydrogen desorption temperature and increased released hydrogen content.