Thermodynamic properties and absorption-desorption kinetics of Mg87Ni10Al3 alloy synthesised by reactive ball milling under H2 atmosphere

Abstract

In this work, the synthesis of Mg87Ni10Al3 hydride by reactive ball milling under H2 atmosphere is presented. Reactive milling under hydrogen induces the conversion of Mg into nanocrystalline MgH2 (final crystallite sizes ∼8 nm). The percentage of the hydride increases with the milling time and after 20 h of mechanical treatment the reaction is complete. Only at longer milling time, when a high conversion degree of Mg into the hydride is reached, the reaction with Ni to form Mg2NiH4 is observed. Thermal analysis shows that, for the shorter milling time, the decomposition of the hydride starts at ∼200 ◦C, but the stability of the hydride slightly increases with increasing milling time. Fast absorption–desorption kinetics is obtained at 300 ◦C.