Segregation of solute elements and strengthening effects of CoCrNiCux medium-entropy alloys: A combined experimental and simulation study

Segregation of solute elements and strengthening effects of CoCrNiCux medium-entropy alloys (MEAs) was investigated by a combination of experiments and Metropolis Monte Carlo (MC) simulations. Results revealed that the proper addition of Cu effectively improved the tensile strength and yield strength, which was attributed to the dual action of solid solution strengthening and grain refinement caused by the pinning of nano-size Cu-rich precipitates. Micro-voids readily nucleated at the interface between the Cu-lean and Cu-rich phases due to local uneven stress distribution and dislocation pile-ups, thereby promoting the crack initiation and propagation. Based on Metropolis MC simulations, the annealed structures revealed a typical local ordering character, and the short-range order (SRO) parameter revealed the atomic interactions and local chemical ordering of CoCrNiCu1.0 MEA.