Abstract: The serratedflow of alloy LC9 with different regimes of heat treatment has been investigated at constant rate of stretching.The critieal strain ε_c at the starting of serrated flow increases with the extension of aging.The activation energy of the process is 0.63 e V which is consistent with the diffusion activation energy of vacancies in A1.The ε_c decreases while the strain rate ε increases,i.e.,with negative strain rate relation.This relation is contrary to that of the an- nealed samples.It shows that the serrated 17ow of annealed sample is controlled by deformation vaeancies,and that of aged sample is controlled by quenching vacancies.The den- sity and shape of the serration are changed by aging.The mechanism of the above mentioned results is discussed.

Key words: serratedflow, Cottrell atmosphere, aging, pinning and depinning