Microstructural development in nanocrystalline during H-absorption/desorption cycling

Repeated dehydriding/hydriding cycles of ball-milled nanocrystalline MgH 2 powders were carried out in a Sievertʹs-type apparatus. The microstructural changes during cycling were characterized by X-ray diffraction. Using the convolutional multiple whole profile fitting procedure, several microstructural parameters, i.e. the average grain size and the grain-size distribution of the as-milled and treated samples were determined. Based on the shrinking core model, the significant difference between the microstructures obtained after the first and repeated cyclings was explained.