Diffusion of Hydrogen in Copper-Palladium Alloys

Abstract

The diffusion of hydrogen in copper-palladium alloys has been studied by utilizing the dependence of electrical resistivity upon hydrogen concentration—a technique both rapid and simple. At 25°C the diffusion coefficient in the range 0–58 at.% Cu is relatively insensitive to alloy composition but is extremely sensitive to the α-β phase change: it increases two orders of magnitude to become 5×10−5 cm2/sec when the crystal structure of the alloy system changes from face-centered cubic to ordered body-centered cubic. Measurements at 130°C indicate that this large increase is due to a decrease by a factor of three in the activation energy for diffusion. The ratio of the diffusion coefficient for hydrogen to that for deuterium in the body-centered cubic alloy was found to be approximately 1.5.