A SIMULATION STUDY OF THE MIGRATION AND COALESCENCE OF GAS-BUBBLES INMETALS

In this work the evolution of inert gas bubble microstructures by migr ation and coalescence has been simulated systematically on the basis o f Smoluchowski's coagulation equations for two typical experimental co nditions: (A) coarsening at constant gas content (annealing after low temperature irradiation/implantation) and (B) bubble evolution under c ontinuous gas production at elevated temperatures (hot irradiation/imp lantation). The number of rate equations which had to be taken into co nsideration, could be limited by proper repopulation procedures. As a result of the integrations we obtain the time evolution of the bubble size distributions, the bubble densities and the mean bubble radii. We show that in the case of constant gas content, the bubble size distri butions become asymptotically self-similar, whereas under continuing g as supply there is no simple scaling behaviour. In both cases the size distributions are monomodal and the asymptotic time dependences of th eir moments follow simple power laws. The asymptotic time dependences of the bubble densities and radii are discussed.