Some microstructural aspects of hydriding internally oxidized Pd-Al alloys

Microstructural studies of internally oxidized Pd-Al alloys have been carried out using scanning electron microscopy. Pd nodules form by extrusion of Pd from the bulk while vacancies are transported from the surface during the formation of the internal oxide precipitates. The result is a dimpled honeycomb appearance in the subsurface region as seen along grain walls. Extensive intergranular cracking occurs during internal oxidation. When the internally oxidized alloys are hydrided/dehydrided, cracking is accentuated with transgranular cracks developing. Significant enhancement in the rates of hydriding and dehydriding have been observed after internal oxidation. (C) 1999 Elsevier Science S.A. All rights reserved.