Segregation behavior in proton- and heavy-ion-irradiated ferritic–martensitic alloys

Radiation-induced segregation at grain boundaries, precipitate/matrix interfaces, and dislocations were analyzed using atom probe tomography in ferritic–martensitic alloys HCM12A, T91 and HT-9 following proton irradiation to 7 dpa at 400 °C and in HCM12A following Fe2+ ion irradiation to 100 dpa at 500 °C. Segregation of Cr varied considerably among grain boundaries (from depletion to enrichment). However, segregation of Ni, Si, Mn, P (enrichment) and W (depletion) at grain boundaries was rather consistent. Radiation-induced segregation at 100 dpa by Fe2+ was very comparable to that at 7 dpa by protons in both segregation tendencies and magnitudes in HCM12A. Although segregation magnitudes varied, similar segregation tendencies at sinks were observed among HCM12A, T91 and HT-9. Cr, Ni, Si and P tended to enrich at precipitate/matrix interfaces, which may promote the formation of new phases at these sites. Enrichment of Ni and Si at sinks was consistently observed in the three alloys regardless of sink types (grain boundaries, dislocations or the precipitate/matrix interfaces of the Cr carbides).