On the atomic-scale solute redistribution during the annealing of cold-rolled high-strength Ni-Co-Cr-Mo-based medium entropy alloy

In this work, we show atomic-scale solute redistribution during annealing in the cold-rolled deformed microstructure of Co-32Ni-24Cr-6Mo (at. %) alloy. Using correlative structural and compositional analysis, we reveal that the derived strengthening is critically a consequence of Mo/Co segregation to deformation-induced stacking faults (SFs) and nano-twins (NTs), and partitioning to the nano-martensite laths (NMLs). These observations establish that Suzuki-type solute segregation and solute-partitioned hcp laths (SP-NMLs) jointly underpin the observed hardening during annealing. The results resolve the ongoing debate regarding solute diffusion behaviour in the alloys and highlight Mo/Co–defect interactions as the key source of strength.