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Irradiation-induced segregation at grain boundaries

APT, spallation transmutants
APT characterization of the irradiation-induced segregation behavior of spallation transmutants

ODS ferritic/martensitic steels are promising candidate structure materials for future reactors. The transmutants produced in spallation targets could affect the materials’ microstructure[1]. The spallation transmutants were quantitatively measured and localized in the steels after irradiation. This study shows their grain boundary segregation behavior for the first time. The transmutants Ti, Ca, Sc and K enrich at the grain boundary, ODS particles and h phase. Many publications suspect that over-size atoms should deplete at grain boundaries in ferritic/martensitic steels. However, these transmutants, as over-size elements, demonstrate different irradiation-induced segregation behavior at grain boundaries.

Recorded on CAMECA LEAP 4000X-HR at ETH, Zurich, Switzerland. Image courtesy of L. Cui.
L. Cui, S. Gerstl, Y. Dai. [1] V. Kuksenko et al. Production and segregation of transmutation elements Ca, Ti, Sc in the F82H steel under mixed spectrum irradiation of high energy protons and spallation neutrons, Journal of Nuclear Materials, 447(1–3), pp. 189–196. (2014)

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