Influences of strain rate on superplasticity of TA15 alloy were investigated by constant strain-rate tensile method.The results show that the elongation is increased gradually with decreasing in strain rate at 900 ℃ and strain rate in range of 3.3×10-4～1.1×10-2 s-1

and the maximum elongation of 1074% can be observed

and the better superplasticity can be also obtained at the high strain rate.Moreover

the extensive strain hardening stages appear in the curves of strain-stress.The lower the strain rate is

the longer the strain hardening stage is

and it is in favor of superplastic deformation.The microstructure observation shows that the strain rate is closely related with microstructure evolution.The lower the strain rate is

the more serious the microstructure coarsening is.Additionally

at the high stain rate

lots of new fine equaxied α phase appear in the deformed region of the specimen as a result of dynamic recrystallization.