Consequences of lattice expansive strain gradients on hydrogen loading in palladium

Abstract

Hydrogen dissolves in metals by occupying interstitial positions and expanding the lattice. It follows that a stress field is generated by the loading process itself. The aim of this paper is to discuss, on the basis of experimental results, whether the stress field is responsible for the force which limits the attainment of high concentrations of hydrogen in massive palladium samples. A calculation of the H/Pd concentration shows that stress-field relaxation aids the hydrogen uptake and our experimental results show that a suitable loading path can improve the final loading ratio.