Excellent tensile property and its mechanism in Al0.3CoCrFeNi high-entropy alloy via thermo-mechanical treatment.

Al 0.3 CoCrFeNi is one of the widely studied high-entropy alloys (HEAs) due to the superior properties; however, its strength at room temperature is not satisfactory. The thermo-mechanical method was usually used to tune the mechanical property of materials. Here the as-cast Al 0.3 CoCrFeNi HEA was cold rolled and subsequently annealed for various times. The microstructural variation was characterized by X-ray diffraction, electron backscatter diffraction and transmission electron microscopy and the mechanical properties were estimated by microhardness and tension tests. It was found that the shorter annealing time led to a finer grain size and higher hardness. Besides, the yield strength of ~467 MPa, ultimate tensile strength of ~830 MPa and tensile elongation of ~48% were achieved in the thermo-mechanically processed alloy, which was comparable with or even a little higher than the previously reported data. The excellent combination of strength and ductility in this alloy was mainly ascribed to the combined action of residual dislocations, refined grains, and annealing and deformation twins in the dislocation motion. The calculated results of the contributions from different strengthening mechanisms to yield strength were well consistent with the experimental data. • Room-temperature property of HEA was tuned by thermo-mechanical method. • The balanced strength and ductility of Al 0.3 CoCrFeNi HEA were achieved. • Action of multiple microdefects in dislocation motion leads to improved property. • Yield strength was well predicted based on different strengthening contributions [ABSTRACT FROM AUTHOR]