Abstract: Effect of annealing temperature on microstructure and properties of the as-cast CoCrFeNiMn high entropy alloy was studied by annealing at different temperatures (600, 850 and 1000 ℃). The results show that both the as-cast and annealed CoCrFeNiMn high entropy alloys have a single-phase FCC structure, the microstructure is a typical dendritic structure, and there are grain like particles precipitated between dendrites. Compared with the as-cast state, after annealing at 600 ℃, the precipitates in the alloy are discontinuous and redissolved, the tensile strength increases to 468.21 MPa, the elongation after fracture increases to 42.38%, and the hardness decreases to 143 HV0.2. After annealing at 850 ℃, the precipitates in the alloy increase and are uniformly dispersed, the tensile strength decreases to 446.61 MPa, the the elongation after fracture increases to 50.56%, and the hardness increases to 161 HV0.2. After annealing at 1000 ℃, the precipitates in the alloy dissolve again, the tensile strength decreases to 436.54 MPa, the elongation after fracture decreases to 44.54%, and the hardness decreases slightly. By comprehensive comparison, the comprehensive mechanical properties of the alloy annealed at 850 ℃ are the best.

Key words: CoCrFeNiMn high entropy alloy, annealing, precipitates, mechanical properties