Recent progress in the study of mechanisms for enhancing radiation tolerance of materials based on interfaces and nanoprecipitates

Nuclear energy is a vital, clean, reliable, and sustainable energy source emerging as a reliable baseload source of electricity. High-performance structural materials used in nuclear reactors determine the key lifetime of the reactors and thus will be critical for the future success of proposed advances in fission and fusion reactors. These structural materials usually expose to high fluxes of high-energy neutrons and intense thermomechanical stresses. Designing materials from the atomic level to achieve high-radiation tolerance and high-temperature mechanical performances is a long-term challenge in materials research. The irradiation of high-energy neutrons or ions induces point defects in structural materials during service in reactors. These point defects can aggregate to form interstitial clusters, stacking faults tetrahedral, dislocation loops, and voids, leading to hardening, embrittlement, and swelling, eventually degrading the material properties. Interfaces in materials could act as powerful sinks for radiation defects and assist in recombining interstitials and vacancies. Hence, controlling radiation-induced defects via high-density interfaces is one of the major key strategies in designing irradiationdamage-resistant materials in recent decades. In this paper, we reviewed the present progress of the interface-based radiation tolerance enhancement of nanostructured materials with high-density interfaces and how these interfacial structures affect the annihilation of radiation defects. The high density of interfaces was acknowledged to enhance radiation tolerance significantly. The misfit dislocations, orientation relationships, and misfit stress of interfaces play important roles in annihilating the radiation damage to reactor materials and enhancing the radiation tolerance of reactor materials. The areal density of the misfit dislocation interactions could be used to estimate the sink efficiency of semicoherent interfaces. The sink efficiency of interfaces is also related to the orientation relationships of interfaces, as the diffusion direction of point defects is associated with the interface angle between the most possible path of points defects and the interfaces. Additionally, the misfit stress of interfaces could alleviate the radiation damages based on interstitial mechanisms. Further, based on the intrinsic limitations of the strategy enhancing radiation tolerance via nanoscale particles that nanoparticles cannot retain under high-dose irradiation at high temperatures, the nanocrystallization of ODS steels was presented, which is beneficial for the stability of nanoscale oxide particles. Most importantly, the recently reported new strategy for enhancing radiation tolerance via the dynamic disordering-reordering process of ordered metallic nanoparticles was emphasized, e.g., ordered B-2-Ni:(Al, Fe) metallic nanoparticles in Fe75Ni18Al3Mo4 (%) steel. The dominant factors of controlling the sustainable dynamic disordering-reordering process of nanoparticles were discussed, including fully coherent structures with ultralow lattice misfit, very low interfacial energy (similar to 35 mJ m(-2)), suitable Al concentration (3%) and high number density (2x10(24) m(-3)) of the nanoparticles. This new strategy may be easier and more efficient in annihilating defects in high entropy alloys owing to high element concentration in the matrix. Herein, we reviewed the interface microstructures and their roles in annihilating radiation damage in reactor materials. The progress on the design and mechanisms of radiation-resistant materials based on interfaces and the proposed nanoprecipitate dynamic disordering-reordering strategy was highlighted. The current insight into these topics prompts new questions that maintain designing high-irradiation-tolerance materials at the frontier of materials research for years to come.