Irradiation induced clustering in low copper or copper free ferritic model alloys

In order to determine the formation mechanism of solute cluster in ferritic steels under irradiation, Cu and Cu free ferritic model alloys (FeCuMnNiP and FeMnNiP) were irradiated with electrons and ions. Their microstructures were characterized by atom probe tomography and the evolution of the population of point defects was estimated with a model of cluster dynamic. The comparison between experimental results and predictions of the model suggests that the formation of the solute clusters is heterogeneous, on the point defect clusters. The comparison between the experimental results obtained on these two alloys shows that the absence of copper slows down the kinetics of precipitation. Moreover, by comparing the results obtained on the FeCuMnNiP alloy with previous results obtained on binary alloy FeCu, it appears that the presence of manganese, nickel and/or phosphorus slows down the kinetics of precipitation. Finally, the comparison between this study and results obtained by other authors on similar alloys irradiated with neutrons reveals a strong flux effect on the kinetic of precipitation of solute clusters.