Published online by Cambridge University Press: 26 February 2011
The capabilities and complementary nature of atom probe field-ion microscopy (APFIM) and analytical electron microscopy (AEM) for the characterization of finescale microstructures are illustrated by examination of the changes that occur after long term thermal aging of cast CF 8 and CF 8M duplex stainless steels. In material aged at 300 or 400°C for up to 70,000 h, the ferrite had spinodally decomposed into a modulated fine-scaled interconnected network consisting of an iron-rich α′ phase and a chromium-enriched α phase with periodicities of between 2 and 9 nm. G-phase precipitates 2 to 10 nm in diameter were also observed in the ferrite at concentrations of more than 1021 m−3. The reported degradation in mechanical properties is most likely a consequence of the spinodal decomposition in the ferrite.