Abstract
Neutron radiography is used to measure the hydrogen diffusion in metals. It is possible to work in a range of exposures where the optical density distribution on the radiographic film directly represents the hydrogen distribution in the sample. The method is essentially non-destructive and the hydrogen need not penetrate surfaces during the measurement. The diffusion coefficients of H in beta -Ti, V, Nb and Ta in qualities as usually delivered were measured for temperatures between 50 to 110 degrees C. The results indicate that (i) the diffusion coefficient of H in beta -Ti, Nb and Ta is not very sensitive to chemical composition and impurity content and (ii) the diffusion coefficient of H in V is much reduced by cold working without subsequent annealing. It is concluded that for most technical applications regarding the H transport properties it is not necessary to use extremely pure metals.