X-ray diffraction, scanning electron microscopy and magnetic characterization of hydrogenated Ni-Pd alloys

The present work shows results on the surface effects produced by electrolytic hydrogenation and desorption of Ni-Pd alloys (60Ni-40Pd and 40Ni-60Pd, wt.%). The behaviour of these two alloys is rather similar to that of pure nickel rather than pure palladium. Intergranular and transgranular cracks were observed just after the electrolytic charging. During the natural aging the cracks become larger and propagate, as observed by scanning electron microscopy. The hydride phases formed are very unstable at room temperature and normal pressure. X-ray diffractograms were used to obtain a microstrain and microstress analysis of the NiPd solid solution and hydride phases. Magnetization curves of the Ni60-40Pd show that trapped hydrogen atoms remain in the NiPd phase after hydride decomposition and decrease the magnetization saturation and the magnetic permeability. (C) 2004 Elsevier B.V. All rights reserved.