Abstract:Effects of current pulses on superplasticity of cold rolled and 500 ℃ , 30min recrystullizedstates of 2091 Al-Li alloy were investigated. The tension results showed that current pulses madethe elongation of 500 ℃, 30 min recrystallized specimens increase from δ= 290% to δ=390%, and the optimum strain rate of superplastic deformation in cold rolled specimens incrcasefrom ε_opt= 5. 0 × 10^-3 s^-1  to ε_opt= 8. 33 × 1 0^-3 s^-1 , with the same ε_max. Investinnations of me-chanical behaviors indieated that current pulses enhanced the stress strain rate sensitivity expo-nent (500 ℃,30min recrystallized state) and pushed the value of m_max. towards high strain rateregion (cold rolled state). Electron probe analyses showed that current pulses made the soluteatom Cu distribute more homogeneously. It was indicated that the enhancement of m value athigh strain rate by applying current pulses was because homogeneously distributed solute atomsincreased the stress strain rate sensitivity.

Key words: Al-Li alloy current pulse superplasticity