A subnanoscale study of the nucleation, growth, and coarsening kinetics of Cu-rich precipitates in a multicomponent Fe-Cu based steel

The nucleation, growth, and coarsening kinetics of Cu-rich precipitates in a multicomponent Fe-Cu based steel, containing 1.17 at.% Cu, aged at 500 °C for up to 1024 h are investigated. The temporal evolution of the precipitate, heterophase interface, matrix compositions and precipitate morphology are presented. Coarsening temporal exponents are determined for mean radius, (R(t)), number density, Nv(t), and supersaturations, and are compared to the Lifshitz-Slyzov-Wagner model for coarsening, modified for multicomponent alloys by Umantsev and Olson. The experimental results indicate that the alloy does not strictly follow Umantsev -Olson model behavior. Additionally, we compare the results to an investigation of a similar multicomponent steel containing 1.82 at.% Cu and to results in the literature. Furthermore, we present a Thermo-Calc determined phase diagram.