Mechanical properties and deformation behavior of dual-phase Al0.6CoCrFeNi high-entropy alloys with heterogeneous structure at room and cryogenic temperatures

Abstract

Dual-phase Al0.6CoCrFeNi high-entropy alloys (HEAs) with heterogeneous structure are obtained by cold rolling and annealing. Tensile experiments show that this alloy exhibits excellent combinations of yield strength, tensile strength and tensile elongation at room (298 K) and cryogenic (77 K) temperatures. Through the thermodynamic formula, the stacking fault energy of face-centered cube (fcc) phases in Al0.6CoCrFeNi alloys are calculated to be 49.33 mJ/m2 and 28.69 mJ/m2 at 298 K and 77 K, respectively. Combining with EBSD (electron backscattering diffraction) and TEM (transmission electron microscopy), it is concluded that the deformation of dual-phase Al0.6CoCrFeNi alloys with heterogeneous structure at 298 K is mainly dominated by the dislocation slip in fcc plus bcc (body-centered cube) phases, and the deformation mode at 77 K can be divided into two stages: (1) when the true strain is between 0 and 3.8%, the plasticity is mainly caused by dislocation slip of fcc and bcc phases; (2) when the true strain is between 3.8% and samples fracture, the plasticity is mainly induced by deformation twins in fcc phase and dislocation slip in bcc phase.