Samples of Pd0.97Al0.03, Pd0.9Pt0.1 and (Pd0.9Pt0.1)0.97Al0.03 alloys, cold worked and internally oxidized at 1073K for 72h were submitted to a H permeation test at 313K, using two levels of cathodic charging current for H generation, equal to 0.1 and 20mA. The effects of internal oxidation were investigated by X-ray diffraction and transmission electron microscopy. The formation of prismatic nano-precipitates of Al2O3 was observed by transmission electron microscopic analyses in Pd0.97Al0.03. However, in the (Pd0.9Pt0.1)0.97Al0.03 alloy, the formation of Al2O3 was not observed, which suggested that the addition of Pt to Pd–Al inhibited the internal oxidization of Al. Cold-working and the addition of Al and Pt to Pd contributed to decreases in the H diffusion coefficient. On the other hand, it increased the apparent H solubility, Sapp. This increase was more effective for Pd0.97Al0.03 samples, where Sapp=1075molH/m3. A great deviation in the H permeation curve, performed at 20mA, was observed for Pd0.97Al0.03 internally oxidized, which indicated hydride formation during the test. This behavior was observed for oxidized Pd0.97Al0.03 but not for the (Pd0.9Pt0.1)0.97Al0.03 alloy.

Hydrogen Diffusivity and Solubility in Palladium Alloys. D.S.dos Santos, V.M.Azambuja, L.Pontonnier, S.Miraglia, D.Fruchart: Journal of Alloys and Compounds, 2003, 356-357, 236-9