Effect of Mn interfacial segregation on the coarsening behavior of Cu nanoprecipitates in a high-Mn austenitic steel

Precipitation of Cu-enriched nanoparticles in steels brings significant precipitation hardening. However, this benefit is often undermined by the coarsening of these coherent precipitates, which leads to a marked performance deterioration. In this work, a Fe-Mn-Cu austenitic steel was designed to investigate the influence of Mn on the precipitation and coarsening behavior of Cu nanoprecipitates. During the early stage of aging at 600 °C, Cu nanoprecipitates nucleated at an ultrahigh number density and were uniformly dispersed within the matrix. With prolonged aging, even after 120 h, the precipitate radius increased only to 4.56 nm with a relative low coarsening rate constant of 0.79 nm3/h. Further analysis suggests that this sluggish coarsening is attributable to the combined effects of Mn segregation at the precipitate/matrix interface and the intrinsically low lattice misfit of approximately 0.52%.