Study on the nucleation and growth of Laves phase in a 10% Cr martensite ferritic steel after long-term aging

•Having used EBSD, SEM–BSE, and TEM techniques to investigate the nucleation and growth of Laves phase in the 10% Cr steel.•Most of Laves phases appear on grain boundaries with a misorientation angle of 40–60° and only a small amount of them at 3–10°.•Carbon atoms will segregate on the vicinity of phase interfaces between Laves phase and α-Fe during decomposition of M23C6 carbides and formation of Laves phases.