Hydrogen diffusivity and solubility were determined by electrochemical H permeation tests in samples of Pd0.97Al0.03 and Pd0.97Ce0.03 in the as received and internally oxidized conditions. Internal oxidization caused the appearance of nano-sized oxide precipitates in the Pd matrix. The shape and size of precipitates and also the coherence between the precipitates and the matrix were observed by transmission electron microscopy. Electrochemical H permeation tests revealed that the presence of oxides increased the apparent H solubility, Sapp, but decreased the H diffusivity, Dapp. The values of Dapp were 2.0 x 10-11m2/s for vacuum heat treated Pd0.97Al0.03 alloy and 4.0 x 10-12m2/s for internally oxidized Pd0.97Al0.03 alloy. However, the concentration of trapped H was 49molH/m3 for the Pd0.97Al0.03 alloy in the vacuum heat treated condition and 403molH/m3 for the Pd0.97Al0.03 alloy in the internally oxidized condition. Both heat treatments were performed at 1073K for 24h. The influence of the nature, size and distribution of the precipitates on the H permeation parameters were considered.

Hydrogen Permeation through Internally Oxidized Pd Alloys. V.M.Azambuja, D.S.dos Santos: Journal of Materials Science, 2007, 42[7], 2255-60