Abstract:The superplastic deformation of aluminium alloy 7475 applied electric current pulse has  been studied. The results presented chat applying a high density current pulse raises hoth the elongation  rate and Ehe m value .and makes supperior superplastic properties at high strain rate of 10^-2s^-1，the op-timum deformation temperature could move from 530 ℃ to 480---510 ℃，TEM observation showed thesuperplastic deformation of the alloy is the results of grain boundary slips and dislocation slips in grains  under funetion of the electron wind; the intergranular tear is a main behavior of fracture of the alloy.

Key words: aluminium alloy 7475  superplasticity  electric  current pulse