Observation of Mn-Ni-Si-rich features in thermally-aged model reactor pressure vessel steels

Atom probe tomography was used to characterise two low-Cu (< 0.04 at. %) model steels after exposure to long-term thermal ageing. Mn-Ni-Si-rich features were observed to form after as little as 20,731 h (similar to 2.4 years) of ageing. The composition of these features were compared to those predicted by thermodynamic models and the similarities and differences are discussed. (C) 2020 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.