Abstract:The hot deformation behaviors of an 2091 Al-Li-Cu-Mg-Zr alloy have been investigated by high temperature isothermal compression testing. The material constants of the alloy, including deformation activation energy ΔH as 162.5 kJ/mol, stress-level coefficientαas 0.039 7 mm²/N, stress exponentialnas 2.647 and structural factorAas 2.74×10¹⁰s^-1  are derived by both graphic representation method and minimized deviation criterion from the interdependencies of flow stress, strain rate and temperature. That the deformation activation energy of the 2091 alloy is higher than the self-diffusion activation energy of pure aluminium for high temperature creep and the activation energy of most other commercial aluminium alloys can be attributed to the alloying of copper and magnesium.

Key words: aluminium-lithium alloy　compression　flow stress　activation energy