The fatigue life of as-extruded magnesium alloy AZ80 in air and NaCl aqueous solution was measured. The mechanism of corrosion fatigue of extruded magnesium alloys and the roles of β phase were investigated. The results showed that ageing can lead to the increase of the volume fraction of β phase and tensile strength and hardness of AZ80, and improve remarkably the fatigue life in corrosive media at lower stress level. Fatigue crack initiated at inclusions on the surface or subsurface of samples, while eman...