Theoretical prediction of radiation-enhanced diffusion behavior in nickel under self-ion irradiation

The enhanced diffusion in materials under irradiation plays an important role in the long-term microstructural evolution. In this work, the self-ion irradiation in nickel was used as a model system to study the effect of radiation-enhanced diffusion on the implanted ion profiles. Initially, the depth profiles of vacancies and implanted ions for nickel self-ion irradiation with ion energies up to 15 MeV were computed by the high-efficiency Monte Carlo code IM3D(Irradiation of Materials in 3 D). The results are in good agreement with those predicted by SRIM(Stopping and Range of Ions in Matter).Then, diffusion coefficients as functions of temperature and damage rate were obtained, and the depth-dependent diffusion coefficients at various temperatures and damage rates were also illustrated. For this purpose, we used a temperature-dependent effective sink concentration for nickel, which was estimated from the available experimental investigations on the damage structures of irradiated nickel. At length, case studies on the time evolution of implanted ion profiles under the condition of nickel selfirradiation were performed and discussed based on Fick’s second law. The results help to understand the fundamental diffusion properties in ion irradiation, especially under higher-dose irradiation.