Structural Changes and Their Kinetics in Hydrogen-Containing Palladium Systems

Non-trivial structural changes and phase transformation kinetics have been found to occur in Palladium-hydrogen and Palladium-metal-hydrogen systems during relaxation processes as hydrogen is released. In the Palladium-hydrogen system these changes take place in stages: an incubation period, a period of fast degassing, a period of stabilisation, and a post-stabilisation period. In Palladium-metal-hydrogen systems the structural changes and phase transformations are non-monotonous (oscillating or stochastic). Time dependent kinetics have been observed over periods of up to tens of thousands of hours. An hypothesis based upon non-equilibrium thermodynamics and hydrogen interaction factors between matrix defects and atoms in the Palladium systems is proposed to explain the phenomena.