HYDROGEN PENETRATION THROUGH STRUCTURAL-MATERIALS DURING HYDROGEN-IONBOMBARDMENT

The hydrogen permeability of 99.98% pure nickel pre-irradiated by the light ions of He, O, N, or C was studied as well as the hydrogen perme ability of the same material under simultaneous bombardment by the sam e light ions and hydrogen ions. The experiments were carried out in th e 100-300 degrees C temperature range. The energy of these light ions used for irradiation was 30 keV, while the irradiation doses varied fr om 1 x 10(21) m(-2) to 1 x 10(23) m(-2). It was found that both of the se types of irradiation caused the hydrogen permeability of the studie d materials to decrease. The extent of decrease in hydrogen permeabili ty was higher in the case of simultaneous bombardment of a sample with the hydrogen ions and ions of one of the light elements mentioned abo ve. Investigations on the hydrogen permeability of nickel and type 16- 15 stainless steel with certain structural features under hydrogen ion bombardment were also carried out. The influence of preliminary cold working (5, 15, 30, and 50%) on the hydrogen penetration as well as th e effect of the grain size on the hydrogen permeability of these mater ials were also investigated. The grain size of the samples was in the 3-5, 30-50, and 400-600 mu m ranges. The experiments were carried out at 150 and 200 degrees C. It was found that preliminary cold working o f the studied materials, as a rule, increased their hydrogen permeabil ity. The investigation of the effect of grain size on the degree of hy drogen penetration through the steel showed that it was practically th e same for the large-grain and medium-grain steel. The hydrogen permea bility of the small-grain steel was about twice as that of the large- and medium-grain steel. Investigations on the hydrogen permeability (H P) through structural materials under simulation of thermonuclear reac tor (TR) working conditions are very important in connection with solv ing the material science problems of controlled thermonuclear fusion ( CTF). (C) 1998 Elsevier Science S.A. All rights reserved.