Behaviour of C, Ni, Si, P under ion irradiation at different doses in model FeCr(Ni, Si, P) alloys

Ferritic-martensitic steels with high chromium content are considered as promising candidates as structural materials in Gen-IV reactors because of their low swelling value for operating conditions and low ductile-brittle transition temperature (DBTT) shift under irradiation. Nevertheless, they tend to harden and embrittle under irradiation at low temperatures (350°C). Impurities as Ni, Si and P are known to increase hardening in these steels by creating solute-rich clusters (SRCs) [1-4].
In order to understand the role of each impurity on the formation of SRCs under irradiation, FeCr (NiSiP) alloys with different concentrations in Ni, Si and P have been ion irradiated with 5 MeV Fe2+ ions up to 0.1, 0.5 and 2.5 dpa at 300°C. The evolution of the solute distribution has been investigated by atom probe tomography (APT).
The results reveal the tendency to cluster of Ni, Si and P under irradiation from 0.1 dpa. Moreover, differences on the solutes distributions between materials containing one low-alloying element (Ni, Si or P) and the alloy containing Ni, Si and P, suggest a synergetic effect between these species. Results show the major role of P on the formation of the SRCs. The influence of C on the formation of SRCs will also be discussed.

References
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