Abstract:The behavior of dynamic recrystallization in the superplastic deformation of 8090 and 2091 aluminum- lithium alloys have been investigated.TEM observations indicated that dynamic recrystallization occurs at the triple junction of grain boundaries.The measurement of grain boundary angle showed that recrystallization in dynamic equilibrium exists in the process of superplastic deformation of 8090 Al-Li alloy.It is also indicated that,besides the role of refining grains and the grain boundary sliding,dynamic recrystallization plays concurrently a role of stablizing microstructure.Thus dynamic rccrystallization can be used to induce metals superplasticity,which leads to a simplification of pretreatment for superplastic deformation.

Key words: dynamic recrystallization; superplasticity; Al-Li alloy; mechanism