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

摘要

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) Cr10Co30Fe30Ni30 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 degrees C for 20 s and at 900 degrees 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 similar to 590 MPa, an ultimate strength of similar to 706 MPa and a total elongation of similar to 23.9%. Additionally, compared with the homogenized counterpart exhibiting homogenous grains, PDA-900-20 s sample displays a notable increment of similar to 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.

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