Abstract: Microstructure, high temperature structure stability and hot workability of the Al₂₅Nb₂₀Ti₃₀Zr₂₅ alloy were studied by means of Thermo-Calc software calculation, microstructure multi-scale characterization and thermal simulation test. The results show that the ingot microstructure of Al₂₅Nb₂₀Ti₃₀Zr₂₅ alloy is mainly composed of BCC matrix and Zr₅Al₃ precipitates. The Zr₅Al₃ phase is continuously precipitated at the BCC grain boundary. The Zr₅Al₃ phase inside the grains is distributed in a block shape with an average size of about 750 nm. After holding at 750-1000 ℃ for 24 h, the grain size of matrix does not change significantly, with the increase of temperature, the content of Zr₅Al₃ phase is decreased slightly, and the high temperature structure stability of alloy is better. The constitutive equation of the alloy is established, $\dot{ε}$=4.5×10¹⁴[sinh(0.0063σ_p)]^2.8exp(-419/RT), and the energy dissipation coefficient map of the alloy is drawn. Under the deformation condition of 1050 ℃/1 s^-1, the energy dissipation coefficient reaches the peak value of 0.69, and under this deformation condition, a complete forging disc without crack is isothermally forged with a size of $\phi$180 mm×20 mm. The original continuous Zr₅Al₃ phases at grain boundary are decomposed into short rods by forging, which are evenly distributed in the BCC matrix, and the BCC matrix undergoes dynamic recovery and partial recrystallization.

Key words: high entropy alloy, microstructure, hot working, properties