A general self-consistent framework for studying cumulative displacement damage in nanostructured metals based on parameter passing and structural feedback between atomic and coarse-grained techniques

摘要: Nano-crystalline metals (NCs) exhibit radiation-tolerance due to the sink of grain boundaries (GBs) for radiation-induced defects such as self-interstitial atoms (SIAs) and vacancies (Vs). However, the relevant mechanisms for the radiation damage accumulation and GB structural relaxation under high radiation field in NCs are still not well understood due to the lack of self-consistent across-scale techniques for simulating radiation-induced microstructures evolution. In this article, by combining coarse-grained and atomistic simulations, we proposed a coupling method to investigate the evolution of the microstructure and SIA/V-GB interaction under cumulative irradiation in NC iron. The SIA overloaded effect was revealed in iron GBs at a high radiation dose rate and/or low temperature. Two types of GB structural response were observed to cumulative irradiation. With the SIA accumulated at the GB, the new GB phase formed and then a critical concentration of the SIA at the GB transited to the small quantity of the V during the GB structural recovery, accompanied by the local GB motion. Consequently, the GB’s role for Vs nearby alternated between the trapping and annihilation center with radiation dose. Alternatively, GB developed to a disordered structure after trapping abundant SIAs. The GB response pattern to cumulative irradiation that is related to the SIA formation energy at the GB or the GB thermal stability is well manifested in the cumulative distribution function of the defects formation energy and its energy level density. The present work reveals the dynamic healing picture for radiation damage near the GB under cumulative irradiation.