Abstract: Selecting Al_11.5Cr₁₆Fe₁₇Ni_51.5V₄ high-entropy alloy as the research object, the microstructure and tensile properties of the alloy with single-phase solid solution treated by solution treatment were studied after aging at 600 ℃ for different time. The results show that the microstructure of the alloy is single-phase FCC solid solution after recrystallization annealing/solution treatment at 1150 ℃ for 7 min. After aging at 600 ℃, nano-sized spherical Ni-rich and Al-rich γ′-Ni₃Al precipitates with L1₂ structure are formed. With the increase of aging time, the size and volume fraction of the precipitated γ′ phase increase monotonously, and the grain size increases slightly. The yield strength of the alloy increases from 306 MPa to 863 MPa, the tensile strength increases from 560 MPa to 1272 MPa, and the alloy maintains good toughness (uniform elongation of 34.1%-17.7%). During aging, the increase of strength is mainly attributed to the precipitation strengthening of the γ′ phase, where the mechanism is the dislocation cutting. The γ′ precipitation strengthening effect increases with the increase of size and volume fraction of the precipitated γ′ phase. The good toughness of the alloy depends on the coherent characteristics of the precipitated γ′ phase and the extremely small nano-size, which reduces the stress concentration at the precipitated phase/matrix interface.

Key words: high-entropy alloy, aging treatment, precipitation strengthening, γ′precipitates with L1₂ structure, mechanical properties