Hierarchical Cu-Rich Nanoprecipitates in a CoFeTiVCu High-Entropy Alloy and Its Impressed Strength-Plasticity Balance

Structural diversity, like chemical composition and morphology, is an important originating point of various mechanical properties. The exploration of these properties has been motivated by the fertile compositional constituents of multicomponent alloys/high-entropy alloys (HEAs). Herein, hierarchical Cu-rich precipitates embedded in a BCC matrix were found and highlighted in an equimolar CoFeTiVCu HEA. The Cu-rich precipitates were branched into two main classifications: nanoscale particles and micron lath/irregular shapes. Among them, the nanoparticles were almost evenly distributed in the overall region, which was attributed to the dramatically decreased solubility of Cu in the BCC matrix as the temperature decreased and that Cu quickly diffused. Alternatively, the others formed directly from the Cu-rich liquid during the solidification process. These kinds of hierarchical precipitates, combined with the great solid solution strengthening in the BCC matrix, gave rise to an excellent combination of strength and plasticity, specifically a yield strength, fracture strength, and compressive plasticity as high as 1.9 GPa, 2.2 GPa, and 7%, respectively. Graphical Abstract