Kinetics of the growth of helium bubbles at the grain boundaries. Formation of the spatially inhomogeneous distribution of helium bubbles near the grain boundaries

In the present paper the kinetics of nucleation and development of gas bubbles near and at the grain boundaries have been investigated. A self-consistent theoretical calculation of the diffusion growth of three ensembles of gas bubbles has been made: bubbles at the grain boundaries, bubbles on dislocations and bubbles in the grain interior. Emphasis is placed on investigating the influence of the spatially inhomogeneous distribution of the dislocation density on the kinetics of growth of ensembles of gas bubbles. The theory formulated makes it possible to explain the more rapid growth of bubbles at the grain boundaries in comparison with the growth of bubbles on dislocations and in the grain interior. We have obtained a spatially inhomogeneous distribution of gas bubbles near the grain boundaries. The basic results of the theory are compared with the results of an experiment on the kinetics of nucleation of helium bubbles under the conditions of annealing near and at the grain boundaries in polycrystal nickel irradiated with alpha particles. (orig.)