Hydrogen absorption kinetics and hydrogen distribution of Ti-6Al-4V alloy

The hydrogenated tests of Ti-6Al-4V alloy were carried out at 750℃ and the hydrogen absorption kinetics was analyzed. The effect of holding time on the hydrogen distribution was studied by optical microscope and secondary ion mass spectrometry. The results show that the hydrogen absorption kinetics of Ti-6Al-4V alloy obeys the two-dimensional diffusion mechanism, in agreement with the Valensi equation g(α)=α+(1-α)ln(1-α), and thus the hydrogen diffusion is a rate-controlling step in the diametric direction of the sample. When the holding time is more than 60min, the hydrogen pressure becomes stable, hydrogen stops diffusing in the diametric direction of the sample, and the microstructure and hydrogen ion intensity at the center are the same as those at the brim during hydrogenation process, which proves that hydrogen distributes uniformly within the sample.