Effect of annealing treatment on the mechanical properties and corrosion behaviour of Co 40 Cr 20 Ni 30 Al 4.5 Ti 5 Mo 0.5 high-entropy alloy

Cast high-entropy alloys are frequently found to have large internal tensions, compositional segregation, and shrinkage defects, which can directly prevent them from performing as intended. Proper heat treatment can modify the internal structure of an alloy and enhance its overall performance. This study describes a new nonequiatomic proportional cast Co 40 Cr 20 Ni 30 Al 4.5 Ti 5 Mo 0.5 high-entropy alloy prepared by a vacuum induction melting technique. The impacts of different annealing temperatures (700, 800, 900, and 1000 degrees C) on the microstructure evolution mechanism, mechanical properties and corrosion behaviour of the alloy are systematically examined. The results show that the heat treatment can successfully improve the overall mechanical properties and corrosion resistance of high-entropy alloys while suppressing casting defects. The alloy exhibits the best overall mechanical properties after annealing at 700 degrees C, with a yield strength of 923 MPa and a tensile strength of 1090 MPa. After annealing at a temperature of 800 degrees C, the alloy demonstrates excellent corrosion resistance, characterized by a low passivation current density, a large passivation range, and a high corrosion potential. Specifically, i pass is measured to be 4.59 x 10 -7 A/cm 2 , and E corr is -319 mV. Furthermore, the maximum Cr 2 O 3 oxide content in the alloy passivation film formed at 800 degrees C contributes to the passivation film stability.