Statistical characteristics of prismatic dislocation loops coagulating by glide and conservative climb

Thermal exposures on metallic structural materials used in the nuclear industry may involve microstructural changes. As modeling and experiments have shown, the coarsening process of radiation-induced prismatic loops in the course of thermal annealing results in greater spatial homogeneity and stability of deformation when followed by plastic loading. On the other hand, loop coarsening deteriorates the material’s resistance to thermal creep. In the operating temperature range used for structural materials in nuclear applications, the volume diffusion of vacancies is small. The change in the loop’s size and density occurs due to the migration caused by elastic interactions. As glide results in trapped configurations, the slower process of conservative climb is a key recovery process under these moderate temperatures. The article presents the Monte Carlo modeling of the evolution of prismatic loop statistic parameters in the course of annealing with varying initial shares of vacancy loops. The radial correlation function normalized to the average interloop distance becomes time-independent after the loop concentration decreases by half. The calculation results are used to construct equations for the change in concentration, radial correlation function, and size distribution function of prismatic loops during coagulation involving glide coupled with conservative climb. The evolution of the size distribution function and the change in the relative number of dominant type of loops can serve as an auxiliary tool to verify the nature of the loop coarsening process in specific experiments, along with the traditional evaluation of activation energy from the changes in the loop’s concentration and mean size.