The Effect of Included Hydrogen on the Motion Parameters of Edge Dislocations in Palladium Membranes

The effect of included hydrogen on the mechanical and transport properties of palladium membranes is discussed. The dissolution of hydrogen in palladium changes the properties of the metal and can result in its hydrogen embrittlement and cracking, which depends on the motion parameters of dislocations. During the slipping motion of edge dislocations, hydrogen atoms affect the Peierls activation barrier. During the creeping motion, the included hydrogen affect the diffusivities of interstitial metal atoms. On the basis of the atomic model, the concentration dependence of the shear modulus, as well as the self-diffusivities and mass transfer coefficients of the included hydrogen and palladium atoms, is analyzed. The rates of elementary jumps of included atoms between interstitial sites are calculated according to the transition state model for imperfect reaction systems. An increase in the concentration of included hydrogen at the change in the phase state of the membrane under nonequilibrium conditions is shown to reduce the mobility of edge dislocations and promote the accumulation of internal stress.[PUBLICATION ABSTRACT]