Fatigue fracture features such as pseudo- and fatigue striations were investigated for the Al-alloys AL-Si-Mg and Acoustic Emission (AE) was used to analyze plastic deformation processes ahead of a crack tip. Dramatic change of fatigue striations spacing was demonstrated in accordance with AE-signals evolution. Specimens with fatigue crack have not macroscopic significance in plastic deformation process under tension up to the fast fracture when striation spacing is over 2.1x10-7 m. Mechanisms of material deformation and fracture around of a crack tip during fatigue striations formation process are discussed on the bases of the synergistic approach.