Clustering Effects Under Irradiation in Fe-0.1%Cu Alloy : An Atomic Scale Investigation with the Tomographic Atom Probe

In order to understand the effect of displacement cascades on the evolution of the microstructure of ferritic low copper supersaturated materials, analyses by 3D atomic tomography of neutron, electron and self ion irradiated Fe-0.1%Cu, were performed. This alloy was chosen because of its low copper concentration, close to that of french pressure vessel steels. The comparison of the microstructure evolutions in these irradiated specimens reveals the appearance of tiny copper "clusters" or "aggregates" only when displacement cascades are involved, namely under ion or neutron irradiation. These results lead to the conclusion that displacement cascades or mixing of atoms (instead of enhanced diffusion) have a specific role on the behavior and the evolution of the solid solution of this binary alloy. 3D observation of these clusters was achieved using the tomographic atom probe