Some microstructural aspects of hydriding internally oxidized Pd-Al alloys

Microstructural studies of internally oxidized Pd-Al alloys have been carri ed out using scanning electron microscopy. Pd nodules form by extrusion of Pd from the bulk while vacancies are transported from the surface during th e formation of the internal oxide precipitates. The result is a dimpled hon eycomb appearance in the subsurface region as seen along grain walls. Exten sive intergranular cracking occurs during internal oxidation. When the inte rnally oxidized alloys are hydrided/dehydrided, cracking is accentuated wit h 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.