Mechanism of hydrogen capacity dependence on the hydrogenation temperature

It is known that decreasing the hydrogenation temperature results in a loss of hydrogen capacity of Mg powders. Based on the model that hydrogen capacity is reached when hydride colonies/crystals formed on the surface of particles impinge on each other and form a continuous layer, it is elucidated, through a two-step hydrogenation experiment and detailed microstructural analysis, that the reduced hydrogen capacity at low temperatures is associated with an increase in the hydride nucleation rate. (C) 2009 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.