Modeling of irradiation growth of Zr single crystals with diffusion anisotropy

Abstract

To predict the irradiation deformation of hexagonal materials, a cluster dynamics model is proposed in this study describing the evolutions of point defects and defect clusters with the diffusion anisotropy of self-interstitial atoms involved. Nucleation and growth models for 〈c〉 vacancy, 〈a〉 interstitial, and 〈a〉 vacancy dislocation loops are developed. Irradiation growth strains are obtained considering the defect formation, growth of dislocation loops, and climb of dislocations. Simulated growth strains along a- and c-axes agree well with the experimental data of annealed and pre-deformed Zr single crystals irradiated at different temperatures. It is found that the dominant contributions to the growth strains by different deformation mechanisms are changed by varied dislocation densities. The irradiation growth could be greatly affected by diffusion anisotropy due to the variation in the absorption efficiency of point defects by sinks. This study reveals the deformation mechanisms in the irradiation growth of Zr single crystals and could provide an effective calculation model for the irradiation deformation of hexagonal materials.