The H desorption properties of the pure Al and of the Al alloy were investigated by means of thermal desorption spectroscopy. In the case of the H thermal desorption spectrum, 2 peaks in the temperature were observed which were thought to correspond to desorption that was due to second-order surface reactions and diffusion. The activation energy for desorption, due to surface reaction, was equal to 38kJ/mol in the case of AA1050. In the case of AA1001, the activation energy and diffusion constant of H were calculated, by using a simple diffusion model, to be 50kJ/mol and 0.0005 to 0.0035cm2/s, respectively. The H which was desorbed from the Al alloy was estimated to be 0.159cm3 per 100g of Al. This was twice the equivalent value for AA1050.

Hydrogen Desorption Behavior of Aluminium Materials Used for Extremely High Vacuum Chamber. Y.Hirohata, S.Fujimoto, T.Hino, T.Yamashina: Journal of Vacuum Science and Technology A, 1993, 11[5], 2637-41