Strain-induced dissolution of Cu–Mg co-clusters and dynamic recrystallization near a fatigue crack tip of an underaged Al–Cu–Mg alloy during cyclic loading at ambient temperature

The microstructure evolution near a fatigue crack tip of an underaged Al–Cu–Mg alloy indicated that cyclic deformation around the crack tip was a kind of severe localized plastic deformation. It was first revealed that the dissolution of Cu–Mg co-clusters was directly related to the repeated cutting by moving dislocations as intense localized cyclic straining at the fatigue crack tip was applied. A transition from the dislocation tangles to subgrains, which was associated with room-temperature dynamic recrystallization, was also confirmed.

► Dissolution of Cu-Mg co-clusters was shown to be connected with the repeated cutting of moving dislocations.
► Room-temperature dynamic recrystallization was confirmed near the crack tip as intense localized straining employed.
► Cyclic deformation around the crack tip should be considered as a severe localized plastic deformation.