Effect of Concurrent Pulse in Holding Duration on Superplasticity of 2091Al-Li Alloy

Zhiyi LIU Jianzhong CUI Guangrun BAI Metal Forming Department,Northeastern University,Shenyang,110006,China

摘 要：<正> The effects of concurrent pulses in holding duration on superplasticity of 2091 Al-Li alloy have beeninvestigated in this paper.The results of superplastic deformation showed that concurrent pulses inholding duration decreased the optimum holding time for superplastic deformation(ε=3.33×10^-2 s^,T=500℃)from 15 to 5 min and increased elongation（δ）from 530 to 550%.Themetallographic observations showed that the specimens appliedly by concurrent pulse were com-pletely recrystallized after holding 5 min at 500℃,and grains refined to about 2μm,and those spec-imens unapplied current pulses were partly recrystallized even after holding 15 min at 500℃.theelectron probe analyses indicated that concurrent pulses promoted atomic diffusion.It is pointed outthat concurrent pulses accelerate atom diffusion and dislocation motion.increase nucleation rate ofrecrystallization and decrease the optimum holding time for superplastic deformation and increasesuperplastic properties.

关键词：