An object kinetic Monte Carlo method to model precipitation and segregation in alloys under irradiation

A method based on object kinetic Monte Carlo that can account for segregation and precipitation in metallic alloys in the presence of both vacancies and self-interstitials is presented. Here the model has been applied specifically to FeCr alloys, but could be used for other alloys with proper parametrization. The model is based on the division of the simulation box into cells where only the local concentration of the alloy is considered and not the explicit location of each alloy atom, in a mean field type of approach. This concentration, together with those of neighboring cells, is used to bias defect migration taking into account the proper thermodynamics of the alloy at hand and the stiffness coefficient to include neighboring effects. The novelty of this implementation is, among other things, the explicit description of mixed pairs of point defects with the alloy element: vacancy-Cr (VCr) and self-interstitial-Cr (ICr) whenever necessary. This explicit description allows the temperature dependence of defect evolution to be correctly reproduced. In this paper we present the model in detail for the particular case of processes that take place in the presence of vacancies, to show the robustness and applicability of this method. This work has been carried out within the framework of the EUROfusion Consortium and has received funding from the Euratom research and training programme 2014–2018 under grant agreement No 633053. The views and Opinions expressed herein do not necessarily reflect those of the European Commission. This work has received funding from the Euratom research and training programme 2014–2018 under grant agreement No. 755039 (M4F project) and contributes to the EERA (European Energy Research Alliance) Joint Programme on Nuclear Materials.