The nucleation and growth of nanoscale precipitates in a new class of high-strength, multicomponent, ferritic steels has been studied with complementary state-of-the-art microstructural characterization techniques of atom probe tomography for individual embryos and precipitates and small-angle neutron scattering for their statistical averages. Both techniques revealed a bimodal size distribution, with subnanometer embryos, and nanoscale precipitates. The embryos, which have a radius of ∼0.4 nm, are enriched in Cu and served as preferential sites for nucleation. The critical radius for nucleation was determined to be ∼0.7 nm. Subsequent growth of the precipitates is dictated by volumetric diffusion, as predicted by the Lifshitz–Slyozov–Wagner theory.

• Received 26 October 2011

DOI:https://doi.org/10.1103/PhysRevB.84.174114