Ferritic steels are known to be one of the most used materials. Particularly, high chromium steels have the advantage to present a good resistance to corrosion and to radiation damage. Therefore, they are considered as a promising candidate for advanced fission and future fusion nuclear reactors.
It is known from numerous studies that thermodynamics and kinetics of Fe-Cr alloys are highly sensitive to magnetism. Closely connected to these properties, magnetism also plays an important role on the behaviour of point defects such as vacancies, which control atomic diffusion and microstructural evolution in several conditions.

 Despite the large amount of previous theoretical and experimental efforts, the impact of magnetism on the formation and migration of vacancies in Fe-Cr as a function of temperature and chemical composition is still unclear.

In this work, we first investigate the dependency of vacancy formation energy and migration barriers on the magnetic and chemical configuration of Fe-Cr alloys, via first principles calculations. The obtained data are then used to parameterize a spin-atomic Monte Carlo model [1], in order to perform simulations for an accurate prediction of equilibrium vacancy concentration and vacancy-mediated atomic-diffusion coefficients as functions of temperature for various alloy compositions. The specificity of the present model consists in an explicit treatment of both chemical and magnetic variables, which enables to elucidate the impact of the magneto-chemical interplay on the studied properties [2,3].


References
[1] M.Trochet, F.Soisson, C-C.Fu, M.Lavrentiev, Comp. Mater. Sci., 2021, 199, 110698.
[2] A.Schneider, C-C.Fu, F.Soisson, C.Barreteau, Phys. Rev. Lett., 2020, 124, 215901.
[3] K. Li, C-C. Fu, M. Nastar, F.Soisson, Phys. Rev. B, 2022, 106, 024106.