Transmission electron microscopy study of unhydrided, dehydrided and annealed LaNi\+v\5\-v

The influence of hydrogen absorption on the microstructure of LaNi\+v\5\-v\ powders has been investigated by transmission electron microscopy. At the surface of the unhydrided and dehydrided LaNi\+v\5\-v\ grains a reaction layer is observed. By means of selected area electron diffraction, this layer is found to consist of metallic nickel and a second constituent, most probably La\+v\2\-v\O\+v\3\-v\. This observation suggests that this surface layer is not induced by the hydrogen absorption reaction. Within dehydrided LaNi\+v\5\-v\ grains, planar-like defects were observed. The habit plane, strain field and average spacing of these defects have been determined. (Original abstract-amended)