The rate controlling diffusion process for the growth of helium bubbles in pure nickel

摘要

Pure nickel was implanted homogeneously withabout 1000 appm of helium at room temperature. The formationand growth of helium bubbles during post irradiation annealingwas studied by transmission electron microscopy. Bubbles grew bymigration and coalescence under such experimental condition. Thesizes of the bubbles formed in the bulk and those near thesurfaces/pseudo surfaces were compared. The bubbles formed inthe bulk are smaller by an order of magnitude than those nearsurfaces. The migration rates of bubbles by three possiblemechanisms viz. Vapour transport, volume diffusion and surfacediffusion have been estimated. It is seen that the rate controllingmechanism for growth of bubbles is surface diffusion.