The behavior of polycrystalline aluminum under creep-fatigue interaction at ambient temperature was investigated using optical and transmission electron (TEM) microscopes. The variation in the flow stress with the cumulative strain was determined and correlated with the stages of the development of the dislocations structure. Fracture surfaces were observed by scanning electron microscope (SEM). The obtained results showed that fatigue striation fracture was the dominant fracture mechanism. Moreover, there was no differences observed between the evolved substructure at the steady state of creep-fatigue interaction and the reported results of the steady state of either monotonic creep at high temperature or cyclic straining to large cumulative strain at ambient temperature. It is concluded that the same mechanisms work in either creep and fatigue are working simultaneously during creep-fatigue interaction that enhances
the failure.