Helium mobility and bubble formation in type 316 stainless steel, aluminum, and vanadium

Helium mobility and bubble formation have been studied in Type 316 stainless steel, aluminum, and vanadium by implanting helium using the Naval Research Laboratory (NRL) cyclotron and studying its motion during subsequent annealing experiments. A newly developed α-α elastic scattering technique was used to determine helium concentration profiles in the metals, and quantitative transmission electron microscopy was used to characterize the bubble populations. Bubbles reached visible size at about 0.65 T/sub m/ and continued to grow by a surface diffusion controlled process of bubble migration. Helium loss from cold-worked material was found to be much greater than in annealed material