Temperature-Dependent Irradiation-Induced Clustering in a Fe–Mn–Ni Alloy

The formation of Mn–Ni-rich clusters has attracted huge scientific interests because it is responsible for irradiation-induced hardening of reactor pressure vessel steels. To gain deep insights into the formation of Mn–Ni clusters, the effects of irradiation temperatures on clustering in self-ion-irradiated Fe–Mn–Ni steel at room temperature, 250 °C and 350 °C are studied using atom probe tomography. This research uncovers that the Mn–Ni clusters evolve to different chemistries during irradiation at different temperatures. At room temperature and 250 °C, the Mn/Ni ratios of the clusters evolve toward 1:1, similar to the MnNi phase. At 350 °C, the Mn/Ni ratio of the Mn–Ni clusters evolves toward the Mn 2 Ni phase. Importantly, the clusters with different chemistries exhibit different hardening effects.