Abstrakt
Hydrogen interaction with vacancies and dislocations in Pd were investigated in the present work. Well annealed and plastically deformed Pd samples were electrochemically doped with hydrogen up to various hydrogen concentrations.
Subsequently the samples were subjected to linear annealing (10 K/min) and hydrogen desorption was studied by differential scanning calorimetry (DSC). An endothermic peak caused by hydrogen desorption was observed in the DSC curve of well annealed sample at ~ 178 oC.
In plastically deformed samples this peak is shifted to higher temperatures since hydrogen is trapped at dislocations and its diffusivity is suppressed. Moreover, it was found that if the atmosphere surrounding the heated sample contains oxygen the endothermic hydrogen desorption peak is followed by a strong exothermal peak caused by fusion of desorbed hydrogen with oxygen into water vapour molecules.
To avoid this undesired effect DSC measurements have to be done in a protective atmosphere which does not contain oxygen