Achieving strength–ductility synergy in a non-equiatomic Cr10Co30Fe30Ni30 high-entropy alloy with heterogeneous grain structures

Cold rolling and post-deformation annealing (PDA) heat treatments were used to produce heterogeneous grain structures (HGS) in a single-phase face-centered cubic (fcc) Cr 10 Co 30 Fe 30 Ni 30 high-entropy alloy (HEA). The microstructural evolution and microstructure–property relationship of the HEA were systematically studied under different states. HGS could be achieved in PDA-treated samples at 875 °C for 20 s and at 900 °C for 20 s (PDA-900-20 s). PDA-900-20 s sample exhibits the most excellent combination of strength and ductility, showing a tensile yield strength of ~ 590 MPa, an ultimate strength of ~ 706 MPa and a total elongation of ~ 23.9%. Additionally, compared with the homogenized counterpart exhibiting homogenous grains, PDA-900-20 s sample displays a notable increment of ~ 413% in yield strength and simultaneously maintains a good ductility. The dominated strengthening mechanisms in PDA-900-20 s sample are grain-boundary strengthening and heterogeneous deformation-induced (HDI) strengthening, whereas the good ductility is mainly resulted from the HDI ductility. Accordingly, the present study provides an effective and simple pathway to overcome the strength–ductility trade-off of typical fcc HEAs through heterogeneous microstructure. Graphical abstract