Thermodynamic properties and absorption–desorption kinetics of Mg 87Ni 10Al 3 alloy synthesised by reactive ball milling under H 2 atmosphere

Abstract

In this work, the synthesis of Mg 87Ni 10Al 3 hydride by reactive ball milling under H 2 atmosphere is presented. Reactive milling under hydrogen induces the conversion of Mg into nanocrystalline MgH 2 (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 Mg 2NiH 4 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.