Towards the modeling of the interplay between radiation induced segregation and sink microstructure
Résumé
Excess point defects created by irradiation in metallic alloys diffuse and annihilate at sinks available in the microstructure, such as grain boundaries, dislocations or point defect clusters. Fluxes of defects create fluxes of alloying elements, leading to local changes of composition near the sinks and to a modification of the properties of the materials. The direction and the amplitude of this radiation induced segregation, its tendency to produce an enrichment or a depletion of solute, depends on a set of transport coefficients which are very difficult to measure experimentally. The understanding of radiation induced segregation phenomena has however made significant progress in recent years, thanks to the modeling at different scales of the diffusion and segregation mechanisms. We review here these different advances, and try to identify the key scientific issues that limit the development of predictive models, applicable to real alloys. The review addresses three main issues: the calculation of the transport coefficients from \textit{ab initio} calculations, the modeling of segregation kinetics at static point defects sinks---mainly by kinetic Monte Carlo or diffusion-reaction models---and the more challenging task of modeling the dynamic interplay between radiation-induced segregation and the sink microstructure evolution, especially when this evolution results from the annihilation of point defects. From this overview of the current state-of-the-art in this field, we discuss still-open questions and guidelines for what constitutes, in our opinion, the desirable future works on this topic.
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